linux/drivers/tty/tty_io.c

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/*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
* or rs-channels. It also implements echoing, cooked mode etc.
*
* Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
*
* Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
* tty_struct and tty_queue structures. Previously there was an array
* of 256 tty_struct's which was statically allocated, and the
* tty_queue structures were allocated at boot time. Both are now
* dynamically allocated only when the tty is open.
*
* Also restructured routines so that there is more of a separation
* between the high-level tty routines (tty_io.c and tty_ioctl.c) and
* the low-level tty routines (serial.c, pty.c, console.c). This
* makes for cleaner and more compact code. -TYT, 9/17/92
*
* Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
* which can be dynamically activated and de-activated by the line
* discipline handling modules (like SLIP).
*
* NOTE: pay no attention to the line discipline code (yet); its
* interface is still subject to change in this version...
* -- TYT, 1/31/92
*
* Added functionality to the OPOST tty handling. No delays, but all
* other bits should be there.
* -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
*
* Rewrote canonical mode and added more termios flags.
* -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
*
* Reorganized FASYNC support so mouse code can share it.
* -- ctm@ardi.com, 9Sep95
*
* New TIOCLINUX variants added.
* -- mj@k332.feld.cvut.cz, 19-Nov-95
*
* Restrict vt switching via ioctl()
* -- grif@cs.ucr.edu, 5-Dec-95
*
* Move console and virtual terminal code to more appropriate files,
* implement CONFIG_VT and generalize console device interface.
* -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
*
* Rewrote tty_init_dev and tty_release_dev to eliminate races.
* -- Bill Hawes <whawes@star.net>, June 97
*
* Added devfs support.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
*
* Added support for a Unix98-style ptmx device.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
*
* Reduced memory usage for older ARM systems
* -- Russell King <rmk@arm.linux.org.uk>
*
* Move do_SAK() into process context. Less stack use in devfs functions.
* alloc_tty_struct() always uses kmalloc()
* -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
*/
#include <linux/types.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/devpts_fs.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/console.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/kd.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/seq_file.h>
#include <linux/serial.h>
#include <linux/ratelimit.h>
#include <linux/uaccess.h>
#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/kmod.h>
#include <linux/nsproxy.h>
#undef TTY_DEBUG_HANGUP
#ifdef TTY_DEBUG_HANGUP
# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
#else
# define tty_debug_hangup(tty, f, args...) do { } while (0)
#endif
#define TTY_PARANOIA_CHECK 1
#define CHECK_TTY_COUNT 1
struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
.c_iflag = ICRNL | IXON,
.c_oflag = OPOST | ONLCR,
.c_cflag = B38400 | CS8 | CREAD | HUPCL,
.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
ECHOCTL | ECHOKE | IEXTEN,
.c_cc = INIT_C_CC,
.c_ispeed = 38400,
.c_ospeed = 38400,
/* .c_line = N_TTY, */
};
EXPORT_SYMBOL(tty_std_termios);
/* This list gets poked at by procfs and various bits of boot up code. This
could do with some rationalisation such as pulling the tty proc function
into this file */
LIST_HEAD(tty_drivers); /* linked list of tty drivers */
/* Mutex to protect creating and releasing a tty */
DEFINE_MUTEX(tty_mutex);
static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
ssize_t redirected_tty_write(struct file *, const char __user *,
size_t, loff_t *);
static unsigned int tty_poll(struct file *, poll_table *);
static int tty_open(struct inode *, struct file *);
long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
#ifdef CONFIG_COMPAT
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
#else
#define tty_compat_ioctl NULL
#endif
static int __tty_fasync(int fd, struct file *filp, int on);
static int tty_fasync(int fd, struct file *filp, int on);
static void release_tty(struct tty_struct *tty, int idx);
/**
* free_tty_struct - free a disused tty
* @tty: tty struct to free
*
* Free the write buffers, tty queue and tty memory itself.
*
* Locking: none. Must be called after tty is definitely unused
*/
static void free_tty_struct(struct tty_struct *tty)
{
tty_ldisc_deinit(tty);
put_device(tty->dev);
kfree(tty->write_buf);
tty->magic = 0xDEADDEAD;
kfree(tty);
}
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
static inline struct tty_struct *file_tty(struct file *file)
{
return ((struct tty_file_private *)file->private_data)->tty;
}
int tty_alloc_file(struct file *file)
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
{
struct tty_file_private *priv;
priv = kmalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
file->private_data = priv;
return 0;
}
/* Associate a new file with the tty structure */
void tty_add_file(struct tty_struct *tty, struct file *file)
{
struct tty_file_private *priv = file->private_data;
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
priv->tty = tty;
priv->file = file;
spin_lock(&tty->files_lock);
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
list_add(&priv->list, &tty->tty_files);
spin_unlock(&tty->files_lock);
}
/**
* tty_free_file - free file->private_data
*
* This shall be used only for fail path handling when tty_add_file was not
* called yet.
*/
void tty_free_file(struct file *file)
{
struct tty_file_private *priv = file->private_data;
file->private_data = NULL;
kfree(priv);
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
}
/* Delete file from its tty */
static void tty_del_file(struct file *file)
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
{
struct tty_file_private *priv = file->private_data;
struct tty_struct *tty = priv->tty;
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
spin_lock(&tty->files_lock);
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
list_del(&priv->list);
spin_unlock(&tty->files_lock);
tty_free_file(file);
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
}
/**
* tty_name - return tty naming
* @tty: tty structure
*
* Convert a tty structure into a name. The name reflects the kernel
* naming policy and if udev is in use may not reflect user space
*
* Locking: none
*/
const char *tty_name(const struct tty_struct *tty)
{
if (!tty) /* Hmm. NULL pointer. That's fun. */
return "NULL tty";
return tty->name;
}
EXPORT_SYMBOL(tty_name);
const char *tty_driver_name(const struct tty_struct *tty)
{
if (!tty || !tty->driver)
return "";
return tty->driver->name;
}
static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
const char *routine)
{
#ifdef TTY_PARANOIA_CHECK
if (!tty) {
pr_warn("(%d:%d): %s: NULL tty\n",
imajor(inode), iminor(inode), routine);
return 1;
}
if (tty->magic != TTY_MAGIC) {
pr_warn("(%d:%d): %s: bad magic number\n",
imajor(inode), iminor(inode), routine);
return 1;
}
#endif
return 0;
}
/* Caller must hold tty_lock */
static int check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT
struct list_head *p;
int count = 0;
spin_lock(&tty->files_lock);
list_for_each(p, &tty->tty_files) {
count++;
}
spin_unlock(&tty->files_lock);
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_SLAVE &&
tty->link && tty->link->count)
count++;
if (tty->count != count) {
tty_warn(tty, "%s: tty->count(%d) != #fd's(%d)\n",
routine, tty->count, count);
return count;
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
}
#endif
return 0;
}
/**
* get_tty_driver - find device of a tty
* @dev_t: device identifier
* @index: returns the index of the tty
*
* This routine returns a tty driver structure, given a device number
* and also passes back the index number.
*
* Locking: caller must hold tty_mutex
*/
static struct tty_driver *get_tty_driver(dev_t device, int *index)
{
struct tty_driver *p;
list_for_each_entry(p, &tty_drivers, tty_drivers) {
dev_t base = MKDEV(p->major, p->minor_start);
if (device < base || device >= base + p->num)
continue;
*index = device - base;
return tty_driver_kref_get(p);
}
return NULL;
}
#ifdef CONFIG_CONSOLE_POLL
/**
* tty_find_polling_driver - find device of a polled tty
* @name: name string to match
* @line: pointer to resulting tty line nr
*
* This routine returns a tty driver structure, given a name
* and the condition that the tty driver is capable of polled
* operation.
*/
struct tty_driver *tty_find_polling_driver(char *name, int *line)
{
struct tty_driver *p, *res = NULL;
int tty_line = 0;
int len;
char *str, *stp;
for (str = name; *str; str++)
if ((*str >= '0' && *str <= '9') || *str == ',')
break;
if (!*str)
return NULL;
len = str - name;
tty_line = simple_strtoul(str, &str, 10);
mutex_lock(&tty_mutex);
/* Search through the tty devices to look for a match */
list_for_each_entry(p, &tty_drivers, tty_drivers) {
if (strncmp(name, p->name, len) != 0)
continue;
stp = str;
if (*stp == ',')
stp++;
if (*stp == '\0')
stp = NULL;
if (tty_line >= 0 && tty_line < p->num && p->ops &&
p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
res = tty_driver_kref_get(p);
*line = tty_line;
break;
}
}
mutex_unlock(&tty_mutex);
return res;
}
EXPORT_SYMBOL_GPL(tty_find_polling_driver);
#endif
static int is_ignored(int sig)
{
return (sigismember(&current->blocked, sig) ||
current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
}
/**
* tty_check_change - check for POSIX terminal changes
* @tty: tty to check
*
* If we try to write to, or set the state of, a terminal and we're
* not in the foreground, send a SIGTTOU. If the signal is blocked or
* ignored, go ahead and perform the operation. (POSIX 7.2)
*
* Locking: ctrl_lock
*/
int __tty_check_change(struct tty_struct *tty, int sig)
{
unsigned long flags;
struct pid *pgrp, *tty_pgrp;
int ret = 0;
if (current->signal->tty != tty)
return 0;
rcu_read_lock();
pgrp = task_pgrp(current);
spin_lock_irqsave(&tty->ctrl_lock, flags);
tty_pgrp = tty->pgrp;
tty_check_change(): avoid taking tasklist_lock while holding tty->ctrl_lock May 11 09:42:27 [kernel] [ 1104.496819] rarian-sk-get-c[5630]: segfault at 0 ip 7f478556caf0 sp 7fff8e3fe338 error 4 in libc-2.6.1.so[7f47854f9000+136000] May 11 10:59:48 [kernel] [ 2494.165792] May 11 10:59:48 [kernel] [ 2494.165794] ======================================================= May 11 10:59:48 [kernel] [ 2494.165801] [ INFO: possible circular locking dependency detected ] May 11 10:59:48 [kernel] [ 2494.165805] 2.6.26-rc1-00007-g91b3a7a #217 May 11 10:59:48 [kernel] [ 2494.165807] ------------------------------------------------------- May 11 10:59:48 [kernel] [ 2494.165809] less/7053 is trying to acquire lock: May 11 10:59:48 [kernel] [ 2494.165812] (tasklist_lock){..??}, at: [<ffffffff80232e95>] is_current_pgrp_orphaned+0x15/0x50 May 11 10:59:48 [kernel] [ 2494.165821] May 11 10:59:48 [kernel] [ 2494.165822] but task is already holding lock: May 11 10:59:48 [kernel] [ 2494.165824] (&tty->ctrl_lock){....}, at: [<ffffffff803d5f31>] tty_check_change+0x61/0x110 May 11 10:59:48 [kernel] [ 2494.165831] May 11 10:59:48 [kernel] [ 2494.165832] which lock already depends on the new lock. May 11 10:59:48 [kernel] [ 2494.165833] May 11 10:59:48 [kernel] [ 2494.165835] May 11 10:59:48 [kernel] [ 2494.165836] the existing dependency chain (in reverse order) is: May 11 10:59:48 [kernel] [ 2494.165838] May 11 10:59:48 [kernel] [ 2494.165839] -> #2 (&tty->ctrl_lock){....}: May 11 10:59:48 [kernel] [ 2494.165843] [<ffffffff80253796>] __lock_acquire+0xf86/0x1080 May 11 10:59:48 [kernel] [ 2494.165851] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.165858] [<ffffffff804deee0>] _spin_lock_irqsave+0x40/0x60 May 11 10:59:48 [kernel] [ 2494.165866] [<ffffffff803d31b5>] __proc_set_tty+0x35/0xe0 May 11 10:59:48 [kernel] [ 2494.165873] [<ffffffff803d76d4>] tty_ioctl+0xbf4/0xfe0 May 11 10:59:48 [kernel] [ 2494.165880] [<ffffffff802a05e1>] vfs_ioctl+0x31/0x90 May 11 10:59:48 [kernel] [ 2494.165888] [<ffffffff802a06b3>] do_vfs_ioctl+0x73/0x2d0 May 11 10:59:48 [kernel] [ 2494.165895] [<ffffffff802a095a>] sys_ioctl+0x4a/0x80 May 11 10:59:48 [kernel] [ 2494.165902] [<ffffffff8020b5ab>] system_call_after_swapgs+0x7b/0x80 May 11 10:59:48 [kernel] [ 2494.165910] [<ffffffffffffffff>] 0xffffffffffffffff May 11 10:59:48 [kernel] [ 2494.165924] May 11 10:59:48 [kernel] [ 2494.165925] -> #1 (&sighand->siglock){++..}: May 11 10:59:48 [kernel] [ 2494.165929] [<ffffffff80253796>] __lock_acquire+0xf86/0x1080 May 11 10:59:48 [kernel] [ 2494.165936] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.165943] [<ffffffff804dec1f>] _spin_lock+0x2f/0x40 May 11 10:59:48 [kernel] [ 2494.165951] [<ffffffff8022d5a3>] copy_process+0x973/0x1210 May 11 10:59:48 [kernel] [ 2494.165959] [<ffffffff8022df12>] do_fork+0x82/0x2f0 May 11 10:59:48 [kernel] [ 2494.165967] [<ffffffff8020bfe1>] kernel_thread+0x81/0xde May 11 10:59:48 [kernel] [ 2494.165974] [<ffffffff8020c048>] child_rip+0xa/0x12 May 11 10:59:48 [kernel] [ 2494.165981] [<ffffffffffffffff>] 0xffffffffffffffff May 11 10:59:48 [kernel] [ 2494.166038] May 11 10:59:48 [kernel] [ 2494.166039] -> #0 (tasklist_lock){..??}: May 11 10:59:48 [kernel] [ 2494.166043] [<ffffffff802535ab>] __lock_acquire+0xd9b/0x1080 May 11 10:59:48 [kernel] [ 2494.166050] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.166057] [<ffffffff804dede2>] _read_lock+0x32/0x50 May 11 10:59:48 [kernel] [ 2494.166063] [<ffffffff80232e95>] is_current_pgrp_orphaned+0x15/0x50 May 11 10:59:48 [kernel] [ 2494.166071] [<ffffffff803d5f80>] tty_check_change+0xb0/0x110 May 11 10:59:48 [kernel] [ 2494.166078] [<ffffffff803dac5f>] set_termios+0x1f/0x4c0 May 11 10:59:48 [kernel] [ 2494.166085] [<ffffffff803db379>] tty_mode_ioctl+0x279/0x3e0 May 11 10:59:48 [kernel] [ 2494.166092] [<ffffffff803db51d>] n_tty_ioctl+0x3d/0x260 May 11 10:59:48 [kernel] [ 2494.166100] [<ffffffff803d6c34>] tty_ioctl+0x154/0xfe0 May 11 10:59:48 [kernel] [ 2494.166107] [<ffffffff802a05e1>] vfs_ioctl+0x31/0x90 May 11 10:59:48 [kernel] [ 2494.166114] [<ffffffff802a06b3>] do_vfs_ioctl+0x73/0x2d0 May 11 10:59:48 [kernel] [ 2494.166121] [<ffffffff802a095a>] sys_ioctl+0x4a/0x80 May 11 10:59:48 [kernel] [ 2494.166128] [<ffffffff8020b5ab>] system_call_after_swapgs+0x7b/0x80 May 11 10:59:48 [kernel] [ 2494.166135] [<ffffffffffffffff>] 0xffffffffffffffff May 11 10:59:48 [kernel] [ 2494.166142] May 11 10:59:48 [kernel] [ 2494.166143] other info that might help us debug this: May 11 10:59:48 [kernel] [ 2494.166144] May 11 10:59:48 [kernel] [ 2494.166146] 1 lock held by less/7053: May 11 10:59:48 [kernel] [ 2494.166148] #0: (&tty->ctrl_lock){....}, at: [<ffffffff803d5f31>] tty_check_change+0x61/0x110 May 11 10:59:48 [kernel] [ 2494.166155] May 11 10:59:48 [kernel] [ 2494.166156] stack backtrace: May 11 10:59:48 [kernel] [ 2494.166159] Pid: 7053, comm: less Not tainted 2.6.26-rc1-00007-g91b3a7a #217 May 11 10:59:48 [kernel] [ 2494.166161] May 11 10:59:48 [kernel] [ 2494.166162] Call Trace: May 11 10:59:48 [kernel] [ 2494.166168] [<ffffffff80251223>] print_circular_bug_tail+0x83/0x90 May 11 10:59:48 [kernel] [ 2494.166172] [<ffffffff80250889>] ? print_circular_bug_entry+0x49/0x60 May 11 10:59:48 [kernel] [ 2494.166178] [<ffffffff802535ab>] __lock_acquire+0xd9b/0x1080 May 11 10:59:48 [kernel] [ 2494.166184] [<ffffffff80232e95>] ? is_current_pgrp_orphaned+0x15/0x50 May 11 10:59:48 [kernel] [ 2494.166189] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.166206] [<ffffffff803d5f80>] tty_check_change+0xb0/0x110 May 11 10:59:48 [kernel] [ 2494.166211] [<ffffffff803dac5f>] set_termios+0x1f/0x4c0 May 11 10:59:48 [kernel] [ 2494.166216] [<ffffffff803d3423>] ? tty_ldisc_try+0x23/0x60 May 11 10:59:48 [kernel] [ 2494.166220] [<ffffffff803d3444>] ? tty_ldisc_try+0x44/0x60 May 11 10:59:48 [kernel] [ 2494.166224] [<ffffffff804df2c5>] ? _spin_unlock_irqrestore+0x65/0x80 May 11 10:59:48 [kernel] [ 2494.166230] [<ffffffff803db379>] tty_mode_ioctl+0x279/0x3e0 May 11 10:59:48 [kernel] [ 2494.166234] [<ffffffff803d3444>] ? tty_ldisc_try+0x44/0x60 May 11 10:59:48 [kernel] [ 2494.166239] [<ffffffff803db51d>] n_tty_ioctl+0x3d/0x260 May 11 10:59:48 [kernel] [ 2494.166244] [<ffffffff803d6c34>] tty_ioctl+0x154/0xfe0 May 11 10:59:48 [kernel] [ 2494.166249] [<ffffffff80252baa>] ? __lock_acquire+0x39a/0x1080 May 11 10:59:48 [kernel] [ 2494.166256] [<ffffffff80252baa>] ? __lock_acquire+0x39a/0x1080 May 11 10:59:48 [kernel] [ 2494.166263] [<ffffffff80252baa>] ? __lock_acquire+0x39a/0x1080 May 11 10:59:48 [kernel] [ 2494.166269] [<ffffffff802a05e1>] vfs_ioctl+0x31/0x90 May 11 10:59:48 [kernel] [ 2494.166274] [<ffffffff802a06b3>] do_vfs_ioctl+0x73/0x2d0 May 11 10:59:48 [kernel] [ 2494.166280] [<ffffffff802a095a>] sys_ioctl+0x4a/0x80 May 11 10:59:48 [kernel] [ 2494.166286] [<ffffffff8020b5ab>] system_call_after_swapgs+0x7b/0x80 May 11 10:59:48 [kernel] [ 2494.166292] Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Reported-by: Marcin Slusarz <marcin.slusarz@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-14 23:05:58 +00:00
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
if (tty_pgrp && pgrp != tty->pgrp) {
if (is_ignored(sig)) {
if (sig == SIGTTIN)
ret = -EIO;
} else if (is_current_pgrp_orphaned())
ret = -EIO;
else {
kill_pgrp(pgrp, sig, 1);
set_thread_flag(TIF_SIGPENDING);
ret = -ERESTARTSYS;
}
}
rcu_read_unlock();
if (!tty_pgrp)
tty_warn(tty, "sig=%d, tty->pgrp == NULL!\n", sig);
return ret;
}
int tty_check_change(struct tty_struct *tty)
{
return __tty_check_change(tty, SIGTTOU);
}
EXPORT_SYMBOL(tty_check_change);
static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return 0;
}
static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
return -EIO;
}
/* No kernel lock held - none needed ;) */
static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
{
return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
}
static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}
static long hung_up_tty_compat_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}
static int hung_up_tty_fasync(int fd, struct file *file, int on)
{
return -ENOTTY;
}
static const struct file_operations tty_fops = {
.llseek = no_llseek,
.read = tty_read,
.write = tty_write,
.poll = tty_poll,
.unlocked_ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
.fasync = tty_fasync,
};
static const struct file_operations console_fops = {
.llseek = no_llseek,
.read = tty_read,
.write = redirected_tty_write,
.poll = tty_poll,
.unlocked_ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
.fasync = tty_fasync,
};
static const struct file_operations hung_up_tty_fops = {
.llseek = no_llseek,
.read = hung_up_tty_read,
.write = hung_up_tty_write,
.poll = hung_up_tty_poll,
.unlocked_ioctl = hung_up_tty_ioctl,
.compat_ioctl = hung_up_tty_compat_ioctl,
.release = tty_release,
.fasync = hung_up_tty_fasync,
};
static DEFINE_SPINLOCK(redirect_lock);
static struct file *redirect;
void proc_clear_tty(struct task_struct *p)
{
unsigned long flags;
struct tty_struct *tty;
spin_lock_irqsave(&p->sighand->siglock, flags);
tty = p->signal->tty;
p->signal->tty = NULL;
spin_unlock_irqrestore(&p->sighand->siglock, flags);
tty_kref_put(tty);
}
/**
* proc_set_tty - set the controlling terminal
*
* Only callable by the session leader and only if it does not already have
* a controlling terminal.
*
* Caller must hold: tty_lock()
* a readlock on tasklist_lock
* sighand lock
*/
static void __proc_set_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->ctrl_lock, flags);
/*
* The session and fg pgrp references will be non-NULL if
* tiocsctty() is stealing the controlling tty
*/
put_pid(tty->session);
put_pid(tty->pgrp);
tty->pgrp = get_pid(task_pgrp(current));
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
tty->session = get_pid(task_session(current));
if (current->signal->tty) {
tty_debug(tty, "current tty %s not NULL!!\n",
current->signal->tty->name);
tty_kref_put(current->signal->tty);
}
put_pid(current->signal->tty_old_pgrp);
current->signal->tty = tty_kref_get(tty);
current->signal->tty_old_pgrp = NULL;
}
static void proc_set_tty(struct tty_struct *tty)
{
spin_lock_irq(&current->sighand->siglock);
__proc_set_tty(tty);
spin_unlock_irq(&current->sighand->siglock);
}
struct tty_struct *get_current_tty(void)
{
struct tty_struct *tty;
unsigned long flags;
spin_lock_irqsave(&current->sighand->siglock, flags);
tty = tty_kref_get(current->signal->tty);
spin_unlock_irqrestore(&current->sighand->siglock, flags);
return tty;
}
EXPORT_SYMBOL_GPL(get_current_tty);
static void session_clear_tty(struct pid *session)
{
struct task_struct *p;
do_each_pid_task(session, PIDTYPE_SID, p) {
proc_clear_tty(p);
} while_each_pid_task(session, PIDTYPE_SID, p);
}
/**
* tty_wakeup - request more data
* @tty: terminal
*
* Internal and external helper for wakeups of tty. This function
* informs the line discipline if present that the driver is ready
* to receive more output data.
*/
void tty_wakeup(struct tty_struct *tty)
{
struct tty_ldisc *ld;
if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
ld = tty_ldisc_ref(tty);
if (ld) {
if (ld->ops->write_wakeup)
ld->ops->write_wakeup(tty);
tty_ldisc_deref(ld);
}
}
wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
}
EXPORT_SYMBOL_GPL(tty_wakeup);
/**
* tty_signal_session_leader - sends SIGHUP to session leader
* @tty controlling tty
* @exit_session if non-zero, signal all foreground group processes
*
* Send SIGHUP and SIGCONT to the session leader and its process group.
* Optionally, signal all processes in the foreground process group.
*
* Returns the number of processes in the session with this tty
* as their controlling terminal. This value is used to drop
* tty references for those processes.
*/
static int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
{
struct task_struct *p;
int refs = 0;
struct pid *tty_pgrp = NULL;
read_lock(&tasklist_lock);
if (tty->session) {
do_each_pid_task(tty->session, PIDTYPE_SID, p) {
spin_lock_irq(&p->sighand->siglock);
if (p->signal->tty == tty) {
p->signal->tty = NULL;
/* We defer the dereferences outside fo
the tasklist lock */
refs++;
}
if (!p->signal->leader) {
spin_unlock_irq(&p->sighand->siglock);
continue;
}
__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
put_pid(p->signal->tty_old_pgrp); /* A noop */
spin_lock(&tty->ctrl_lock);
tty_pgrp = get_pid(tty->pgrp);
if (tty->pgrp)
p->signal->tty_old_pgrp = get_pid(tty->pgrp);
spin_unlock(&tty->ctrl_lock);
spin_unlock_irq(&p->sighand->siglock);
} while_each_pid_task(tty->session, PIDTYPE_SID, p);
}
read_unlock(&tasklist_lock);
if (tty_pgrp) {
if (exit_session)
kill_pgrp(tty_pgrp, SIGHUP, exit_session);
put_pid(tty_pgrp);
}
return refs;
}
/**
* __tty_hangup - actual handler for hangup events
2006-11-22 14:55:48 +00:00
* @work: tty device
*
* This can be called by a "kworker" kernel thread. That is process
* synchronous but doesn't hold any locks, so we need to make sure we
* have the appropriate locks for what we're doing.
*
* The hangup event clears any pending redirections onto the hung up
* device. It ensures future writes will error and it does the needed
* line discipline hangup and signal delivery. The tty object itself
* remains intact.
*
* Locking:
* BTM
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* redirect lock for undoing redirection
* file list lock for manipulating list of ttys
* tty_ldiscs_lock from called functions
* termios_rwsem resetting termios data
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* tasklist_lock to walk task list for hangup event
* ->siglock to protect ->signal/->sighand
*/
static void __tty_hangup(struct tty_struct *tty, int exit_session)
{
struct file *cons_filp = NULL;
struct file *filp, *f = NULL;
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_file_private *priv;
int closecount = 0, n;
int refs;
if (!tty)
return;
spin_lock(&redirect_lock);
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
if (redirect && file_tty(redirect) == tty) {
f = redirect;
redirect = NULL;
}
spin_unlock(&redirect_lock);
tty_lock(tty);
tty: Only hangup once Instrumented testing shows a tty can be hungup multiple times [1]. Although concurrent hangups are properly serialized, multiple hangups for the same tty should be prevented. If tty has already been HUPPED, abort hangup. Note it is not necessary to cleanup file *redirect on subsequent hangups, as only TIOCCONS can set that value and ioctls are disabled after hangup. [1] Test performed by simulating a concurrent async hangup via tty_hangup() with a sync hangup via tty_vhangup(), while __tty_hangup() was instrumented with: diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 26bb78c..fe8b061 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -629,6 +629,8 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session) tty_lock(tty); + WARN_ON(test_bit(TTY_HUPPED, &tty->flags)); + /* some functions below drop BTM, so we need this bit */ set_bit(TTY_HUPPING, &tty->flags); Test result: WARNING: at /home/peter/src/kernels/mainline/drivers/tty/tty_io.c:632 __tty_hangup+0x459/0x460() Modules linked in: ip6table_filter ip6_tables ebtable_nat <...snip...> CPU: 6 PID: 1197 Comm: kworker/6:2 Not tainted 3.10.0-0+rfcomm-xeon #0+rfcomm Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11 04/30/2012 Workqueue: events do_tty_hangup 0000000000000009 ffff8802b16d7d18 ffffffff816b553e ffff8802b16d7d58 ffffffff810407e0 ffff880254f95c00 ffff880254f95c00 ffff8802bfd92b00 ffff8802bfd96b00 ffff880254f95e40 0000000000000180 ffff8802b16d7d68 Call Trace: [<ffffffff816b553e>] dump_stack+0x19/0x1b [<ffffffff810407e0>] warn_slowpath_common+0x70/0xa0 [<ffffffff8104082a>] warn_slowpath_null+0x1a/0x20 [<ffffffff813fb279>] __tty_hangup+0x459/0x460 [<ffffffff8107409c>] ? finish_task_switch+0xbc/0xe0 [<ffffffff813fb297>] do_tty_hangup+0x17/0x20 [<ffffffff8105fd6f>] process_one_work+0x16f/0x450 [<ffffffff8106007c>] process_scheduled_works+0x2c/0x40 [<ffffffff8106060a>] worker_thread+0x26a/0x380 [<ffffffff810603a0>] ? rescuer_thread+0x310/0x310 [<ffffffff810698a0>] kthread+0xc0/0xd0 [<ffffffff816b0000>] ? destroy_compound_page+0x65/0x92 [<ffffffff810697e0>] ? kthread_create_on_node+0x130/0x130 [<ffffffff816c495c>] ret_from_fork+0x7c/0xb0 [<ffffffff810697e0>] ? kthread_create_on_node+0x130/0x130 ---[ end trace 98d9f01536cf411e ]--- Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-31 18:05:45 +00:00
if (test_bit(TTY_HUPPED, &tty->flags)) {
tty_unlock(tty);
return;
}
/* inuse_filps is protected by the single tty lock,
this really needs to change if we want to flush the
workqueue with the lock held */
check_tty_count(tty, "tty_hangup");
spin_lock(&tty->files_lock);
/* This breaks for file handles being sent over AF_UNIX sockets ? */
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
list_for_each_entry(priv, &tty->tty_files, list) {
filp = priv->file;
if (filp->f_op->write == redirected_tty_write)
cons_filp = filp;
if (filp->f_op->write != tty_write)
continue;
closecount++;
__tty_fasync(-1, filp, 0); /* can't block */
filp->f_op = &hung_up_tty_fops;
}
spin_unlock(&tty->files_lock);
tty: Signal SIGHUP before hanging up ldisc An exiting session leader can hang if a foreground process is blocking for line discipline i/o, eg. in n_tty_read(). This happens because the blocking reader is holding an ldisc reference (indicating the line discipline is in-use) which prevents __tty_hangup() from recycling the line discipline. Although waiters are woken before attempting to gain exclusive access for changing the ldisc, the blocking reader in this case will not exit the i/o loop since it has not yet received SIGHUP (because it has not been sent). Instead, perform signalling first, then recycle the line discipline. Fixes: INFO: task init:1 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. init D 00000000001d7180 2688 1 0 0x00000002 ffff8800b9acfba8 0000000000000002 00000000001d7180 ffff8800b9b10048 ffff8800b94cb000 ffff8800b9b10000 00000000001d7180 00000000001d7180 ffff8800b9b10000 ffff8800b9acffd8 00000000001d7180 00000000001d7180 Call Trace: [<ffffffff83db9909>] __schedule+0x2e9/0x3b0 [<ffffffff83db9b35>] schedule+0x55/0x60 [<ffffffff83db74ba>] schedule_timeout+0x3a/0x370 [<ffffffff81182349>] ? mark_held_locks+0xf9/0x130 [<ffffffff83dbab38>] ? down_failed+0x108/0x200 [<ffffffff83dbb7ab>] ? _raw_spin_unlock_irq+0x2b/0x80 [<ffffffff81182608>] ? trace_hardirqs_on_caller+0x128/0x160 [<ffffffff83dbab61>] down_failed+0x131/0x200 [<ffffffff83dbbfad>] ? tty_ldisc_lock_pair_timeout+0xcd/0x120 [<ffffffff83dbae03>] ldsem_down_write+0xd3/0x113 [<ffffffff83dbbfad>] ? tty_ldisc_lock_pair_timeout+0xcd/0x120 [<ffffffff8118264d>] ? trace_hardirqs_on+0xd/0x10 [<ffffffff83dbbfad>] tty_ldisc_lock_pair_timeout+0xcd/0x120 [<ffffffff81c3df60>] tty_ldisc_hangup+0xd0/0x220 [<ffffffff81c35bd7>] __tty_hangup+0x137/0x4f0 [<ffffffff81c37c7c>] disassociate_ctty+0x6c/0x230 [<ffffffff8111290c>] do_exit+0x41c/0x590 [<ffffffff8107ad34>] ? syscall_trace_enter+0x24/0x2e0 [<ffffffff81112b4a>] do_group_exit+0x8a/0xc0 [<ffffffff81112b92>] sys_exit_group+0x12/0x20 [<ffffffff83dc49d8>] tracesys+0xe1/0xe6 1 lock held by init/1: #0: (&tty->ldisc_sem){++++++}, at: [<ffffffff83dbbfad>] tty_ldisc_lock_pair_timeout+0xcd/0x120 Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-06 12:20:57 +00:00
refs = tty_signal_session_leader(tty, exit_session);
/* Account for the p->signal references we killed */
while (refs--)
tty_kref_put(tty);
tty: Destroy ldisc instance on hangup Currently, when the tty is hungup, the ldisc is re-instanced; ie., the current instance is destroyed and a new instance is created. The purpose of this design was to guarantee a valid, open ldisc for the lifetime of the tty. However, now that tty buffers are owned by and have lifetime equivalent to the tty_port (since v3.10), any data received immediately after the ldisc is re-instanced may cause continued driver i/o operations concurrently with the driver's hangup() operation. For drivers that shutdown h/w on hangup, this is unexpected and usually bad. For example, the serial core may free the xmit buffer page concurrently with an in-progress write() operation (triggered by echo). With the existing stable and robust ldisc reference handling, the cleaned-up tty_reopen(), the straggling unsafe ldisc use cleaned up, and the preparation to properly handle a NULL tty->ldisc, the ldisc instance can be destroyed and only re-instanced when the tty is re-opened. If the tty was opened as /dev/console or /dev/tty0, the original behavior of re-instancing the ldisc is retained (the 'reinit' parameter to tty_ldisc_hangup() is true). This is required since those file descriptors are never hungup. This patch has neglible impact on userspace; the tty file_operations ptr is changed to point to the hungup file operations _before_ the ldisc instance is destroyed, so only racing file operations might now retrieve a NULL ldisc reference (which is simply handled as if the hungup file operation had been called instead -- see "tty: Prepare for destroying line discipline on hangup"). This resolves a long-standing FIXME and several crash reports. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-11 06:41:06 +00:00
tty_ldisc_hangup(tty, cons_filp != NULL);
spin_lock_irq(&tty->ctrl_lock);
clear_bit(TTY_THROTTLED, &tty->flags);
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
put_pid(tty->session);
put_pid(tty->pgrp);
tty->session = NULL;
tty->pgrp = NULL;
tty->ctrl_status = 0;
spin_unlock_irq(&tty->ctrl_lock);
/*
* If one of the devices matches a console pointer, we
* cannot just call hangup() because that will cause
* tty->count and state->count to go out of sync.
* So we just call close() the right number of times.
*/
if (cons_filp) {
if (tty->ops->close)
for (n = 0; n < closecount; n++)
tty->ops->close(tty, cons_filp);
} else if (tty->ops->hangup)
tty->ops->hangup(tty);
/*
tty: Destroy ldisc instance on hangup Currently, when the tty is hungup, the ldisc is re-instanced; ie., the current instance is destroyed and a new instance is created. The purpose of this design was to guarantee a valid, open ldisc for the lifetime of the tty. However, now that tty buffers are owned by and have lifetime equivalent to the tty_port (since v3.10), any data received immediately after the ldisc is re-instanced may cause continued driver i/o operations concurrently with the driver's hangup() operation. For drivers that shutdown h/w on hangup, this is unexpected and usually bad. For example, the serial core may free the xmit buffer page concurrently with an in-progress write() operation (triggered by echo). With the existing stable and robust ldisc reference handling, the cleaned-up tty_reopen(), the straggling unsafe ldisc use cleaned up, and the preparation to properly handle a NULL tty->ldisc, the ldisc instance can be destroyed and only re-instanced when the tty is re-opened. If the tty was opened as /dev/console or /dev/tty0, the original behavior of re-instancing the ldisc is retained (the 'reinit' parameter to tty_ldisc_hangup() is true). This is required since those file descriptors are never hungup. This patch has neglible impact on userspace; the tty file_operations ptr is changed to point to the hungup file operations _before_ the ldisc instance is destroyed, so only racing file operations might now retrieve a NULL ldisc reference (which is simply handled as if the hungup file operation had been called instead -- see "tty: Prepare for destroying line discipline on hangup"). This resolves a long-standing FIXME and several crash reports. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-11 06:41:06 +00:00
* We don't want to have driver/ldisc interactions beyond the ones
* we did here. The driver layer expects no calls after ->hangup()
* from the ldisc side, which is now guaranteed.
*/
set_bit(TTY_HUPPED, &tty->flags);
tty_unlock(tty);
if (f)
fput(f);
}
static void do_tty_hangup(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, hangup_work);
__tty_hangup(tty, 0);
}
/**
* tty_hangup - trigger a hangup event
* @tty: tty to hangup
*
* A carrier loss (virtual or otherwise) has occurred on this like
* schedule a hangup sequence to run after this event.
*/
void tty_hangup(struct tty_struct *tty)
{
tty_debug_hangup(tty, "hangup\n");
schedule_work(&tty->hangup_work);
}
EXPORT_SYMBOL(tty_hangup);
/**
* tty_vhangup - process vhangup
* @tty: tty to hangup
*
* The user has asked via system call for the terminal to be hung up.
* We do this synchronously so that when the syscall returns the process
* is complete. That guarantee is necessary for security reasons.
*/
void tty_vhangup(struct tty_struct *tty)
{
tty_debug_hangup(tty, "vhangup\n");
__tty_hangup(tty, 0);
}
EXPORT_SYMBOL(tty_vhangup);
/**
* tty_vhangup_self - process vhangup for own ctty
*
* Perform a vhangup on the current controlling tty
*/
void tty_vhangup_self(void)
{
struct tty_struct *tty;
tty = get_current_tty();
if (tty) {
tty_vhangup(tty);
tty_kref_put(tty);
}
}
/**
* tty_vhangup_session - hangup session leader exit
* @tty: tty to hangup
*
* The session leader is exiting and hanging up its controlling terminal.
* Every process in the foreground process group is signalled SIGHUP.
*
* We do this synchronously so that when the syscall returns the process
* is complete. That guarantee is necessary for security reasons.
*/
static void tty_vhangup_session(struct tty_struct *tty)
{
tty_debug_hangup(tty, "session hangup\n");
__tty_hangup(tty, 1);
}
/**
* tty_hung_up_p - was tty hung up
* @filp: file pointer of tty
*
* Return true if the tty has been subject to a vhangup or a carrier
* loss
*/
int tty_hung_up_p(struct file *filp)
{
tty_port: allow a port to be opened with a tty that has no file handle Let us create tty objects entirely in kernel space. Untested proposal to show why all the ideas around rewriting half the uart stack are not needed. With this a kernel created non file backed tty object could be used to handle data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in particular has to work back to the fs/tty layer. The tty_port code is however otherwise clean of file handles as far as I can tell as is the low level tty port write path used by the ldisc, the configuration low level interfaces and most of the ldiscs. Currently you don't have any exposure to see tty hangups because those are built around the file layer. However a) it's a fixed port so you probably don't care about that b) if you do we can add a callback and c) you almost certainly don't want the userspace tear down/rebuild behaviour anyway. This should however be sufficient if we wanted for example to enumerate all the bluetooth bound fixed ports via ACPI and make them directly available. It doesn't deal with the case of a user opening a port that's also kernel opened and that would need some locking out (so it returned EBUSY if bound to a kernel device of some kind). That needs resolving along with how you "up" or "down" your new bluetooth device, or enumerate it while providing the existing tty API to avoid regressions (and to debug). Signed-off-by: Alan Cox <alan@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-By: Sebastian Reichel <sre@kernel.org> Signed-off-by: Rob Herring <robh@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-16 22:54:29 +00:00
return (filp && filp->f_op == &hung_up_tty_fops);
}
EXPORT_SYMBOL(tty_hung_up_p);
/**
* disassociate_ctty - disconnect controlling tty
* @on_exit: true if exiting so need to "hang up" the session
*
* This function is typically called only by the session leader, when
* it wants to disassociate itself from its controlling tty.
*
* It performs the following functions:
* (1) Sends a SIGHUP and SIGCONT to the foreground process group
* (2) Clears the tty from being controlling the session
* (3) Clears the controlling tty for all processes in the
* session group.
*
* The argument on_exit is set to 1 if called when a process is
* exiting; it is 0 if called by the ioctl TIOCNOTTY.
*
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* Locking:
* BTM is taken for hysterical raisins, and held when
* called from no_tty().
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* tty_mutex is taken to protect tty
* ->siglock is taken to protect ->signal/->sighand
* tasklist_lock is taken to walk process list for sessions
* ->siglock is taken to protect ->signal/->sighand
*/
void disassociate_ctty(int on_exit)
{
struct tty_struct *tty;
if (!current->signal->leader)
return;
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
tty = get_current_tty();
if (tty) {
if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) {
tty_vhangup_session(tty);
} else {
struct pid *tty_pgrp = tty_get_pgrp(tty);
if (tty_pgrp) {
kill_pgrp(tty_pgrp, SIGHUP, on_exit);
if (!on_exit)
kill_pgrp(tty_pgrp, SIGCONT, on_exit);
put_pid(tty_pgrp);
}
}
tty_kref_put(tty);
} else if (on_exit) {
struct pid *old_pgrp;
spin_lock_irq(&current->sighand->siglock);
old_pgrp = current->signal->tty_old_pgrp;
current->signal->tty_old_pgrp = NULL;
spin_unlock_irq(&current->sighand->siglock);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
if (old_pgrp) {
kill_pgrp(old_pgrp, SIGHUP, on_exit);
kill_pgrp(old_pgrp, SIGCONT, on_exit);
put_pid(old_pgrp);
}
return;
}
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
spin_lock_irq(&current->sighand->siglock);
put_pid(current->signal->tty_old_pgrp);
current->signal->tty_old_pgrp = NULL;
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
tty: fix memleak in alloc_pid There is memleak in alloc_pid: ------------------------------ unreferenced object 0xd3453a80 (size 64): comm "adbd", pid 1730, jiffies 66363 (age 6586.950s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 40 c2 f6 d5 00 d3 25 c1 59 28 00 00 ....@.....%.Y(.. backtrace: [<c1a6f15c>] kmemleak_alloc+0x3c/0xa0 [<c1320546>] kmem_cache_alloc+0xc6/0x190 [<c125d51e>] alloc_pid+0x1e/0x400 [<c123d344>] copy_process.part.39+0xad4/0x1120 [<c123da59>] do_fork+0x99/0x330 [<c123dd58>] sys_fork+0x28/0x30 [<c1a89a08>] syscall_call+0x7/0xb [<ffffffff>] 0xffffffff the leak is due to unreleased pid->count, which execute in function: get_pid()(pid->count++) and put_pid()(pid->count--). The race condition as following: task[dumpsys] task[adbd] in disassociate_ctty() in tty_signal_session_leader() ----------------------- ------------------------- tty = get_current_tty(); // tty is not NULL ... spin_lock_irq(&current->sighand->siglock); put_pid(current->signal->tty_old_pgrp); current->signal->tty_old_pgrp = NULL; spin_unlock_irq(&current->sighand->siglock); spin_lock_irq(&p->sighand->siglock); ... p->signal->tty = NULL; ... spin_unlock_irq(&p->sighand->siglock); tty = get_current_tty(); // tty NULL, goto else branch by accident. if (tty) { ... put_pid(tty_session); put_pid(tty_pgrp); ... } else { print msg } in task[dumpsys], in disassociate_ctty(), tty is set NULL by task[adbd], tty_signal_session_leader(), then it goto else branch and lack of put_pid(), cause memleak. move spin_unlock(sighand->siglock) after get_current_tty() can avoid the race and fix the memleak. Signed-off-by: Zhang Jun <jun.zhang@intel.com> Signed-off-by: Chen Tingjie <tingjie.chen@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-15 03:52:51 +00:00
tty = tty_kref_get(current->signal->tty);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
if (tty) {
unsigned long flags;
spin_lock_irqsave(&tty->ctrl_lock, flags);
put_pid(tty->session);
put_pid(tty->pgrp);
tty->session = NULL;
tty->pgrp = NULL;
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
tty_kref_put(tty);
} else
tty_debug_hangup(tty, "no current tty\n");
tty: fix memleak in alloc_pid There is memleak in alloc_pid: ------------------------------ unreferenced object 0xd3453a80 (size 64): comm "adbd", pid 1730, jiffies 66363 (age 6586.950s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 40 c2 f6 d5 00 d3 25 c1 59 28 00 00 ....@.....%.Y(.. backtrace: [<c1a6f15c>] kmemleak_alloc+0x3c/0xa0 [<c1320546>] kmem_cache_alloc+0xc6/0x190 [<c125d51e>] alloc_pid+0x1e/0x400 [<c123d344>] copy_process.part.39+0xad4/0x1120 [<c123da59>] do_fork+0x99/0x330 [<c123dd58>] sys_fork+0x28/0x30 [<c1a89a08>] syscall_call+0x7/0xb [<ffffffff>] 0xffffffff the leak is due to unreleased pid->count, which execute in function: get_pid()(pid->count++) and put_pid()(pid->count--). The race condition as following: task[dumpsys] task[adbd] in disassociate_ctty() in tty_signal_session_leader() ----------------------- ------------------------- tty = get_current_tty(); // tty is not NULL ... spin_lock_irq(&current->sighand->siglock); put_pid(current->signal->tty_old_pgrp); current->signal->tty_old_pgrp = NULL; spin_unlock_irq(&current->sighand->siglock); spin_lock_irq(&p->sighand->siglock); ... p->signal->tty = NULL; ... spin_unlock_irq(&p->sighand->siglock); tty = get_current_tty(); // tty NULL, goto else branch by accident. if (tty) { ... put_pid(tty_session); put_pid(tty_pgrp); ... } else { print msg } in task[dumpsys], in disassociate_ctty(), tty is set NULL by task[adbd], tty_signal_session_leader(), then it goto else branch and lack of put_pid(), cause memleak. move spin_unlock(sighand->siglock) after get_current_tty() can avoid the race and fix the memleak. Signed-off-by: Zhang Jun <jun.zhang@intel.com> Signed-off-by: Chen Tingjie <tingjie.chen@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-15 03:52:51 +00:00
spin_unlock_irq(&current->sighand->siglock);
/* Now clear signal->tty under the lock */
read_lock(&tasklist_lock);
session_clear_tty(task_session(current));
read_unlock(&tasklist_lock);
}
/**
*
* no_tty - Ensure the current process does not have a controlling tty
*/
void no_tty(void)
{
/* FIXME: Review locking here. The tty_lock never covered any race
between a new association and proc_clear_tty but possible we need
to protect against this anyway */
struct task_struct *tsk = current;
disassociate_ctty(0);
proc_clear_tty(tsk);
}
/**
* stop_tty - propagate flow control
* @tty: tty to stop
*
* Perform flow control to the driver. May be called
* on an already stopped device and will not re-call the driver
* method.
*
* This functionality is used by both the line disciplines for
* halting incoming flow and by the driver. It may therefore be
* called from any context, may be under the tty atomic_write_lock
* but not always.
*
* Locking:
* flow_lock
*/
void __stop_tty(struct tty_struct *tty)
{
if (tty->stopped)
return;
tty->stopped = 1;
if (tty->ops->stop)
tty->ops->stop(tty);
}
void stop_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->flow_lock, flags);
__stop_tty(tty);
spin_unlock_irqrestore(&tty->flow_lock, flags);
}
EXPORT_SYMBOL(stop_tty);
/**
* start_tty - propagate flow control
* @tty: tty to start
*
* Start a tty that has been stopped if at all possible. If this
* tty was previous stopped and is now being started, the driver
* start method is invoked and the line discipline woken.
*
* Locking:
* flow_lock
*/
void __start_tty(struct tty_struct *tty)
{
if (!tty->stopped || tty->flow_stopped)
return;
tty->stopped = 0;
if (tty->ops->start)
tty->ops->start(tty);
tty_wakeup(tty);
}
void start_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->flow_lock, flags);
__start_tty(tty);
spin_unlock_irqrestore(&tty->flow_lock, flags);
}
EXPORT_SYMBOL(start_tty);
static void tty_update_time(struct timespec *time)
{
unsigned long sec = get_seconds();
/*
* We only care if the two values differ in anything other than the
* lower three bits (i.e every 8 seconds). If so, then we can update
* the time of the tty device, otherwise it could be construded as a
* security leak to let userspace know the exact timing of the tty.
*/
if ((sec ^ time->tv_sec) & ~7)
time->tv_sec = sec;
}
/**
* tty_read - read method for tty device files
* @file: pointer to tty file
* @buf: user buffer
* @count: size of user buffer
* @ppos: unused
*
* Perform the read system call function on this terminal device. Checks
* for hung up devices before calling the line discipline method.
*
* Locking:
* Locks the line discipline internally while needed. Multiple
* read calls may be outstanding in parallel.
*/
static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
{
int i;
struct inode *inode = file_inode(file);
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
if (tty_paranoia_check(tty, inode, "tty_read"))
return -EIO;
if (!tty || tty_io_error(tty))
return -EIO;
/* We want to wait for the line discipline to sort out in this
situation */
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_read(file, buf, count, ppos);
if (ld->ops->read)
i = ld->ops->read(tty, file, buf, count);
else
i = -EIO;
tty_ldisc_deref(ld);
if (i > 0)
tty_update_time(&inode->i_atime);
return i;
}
static void tty_write_unlock(struct tty_struct *tty)
{
mutex_unlock(&tty->atomic_write_lock);
wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
}
static int tty_write_lock(struct tty_struct *tty, int ndelay)
{
if (!mutex_trylock(&tty->atomic_write_lock)) {
if (ndelay)
return -EAGAIN;
if (mutex_lock_interruptible(&tty->atomic_write_lock))
return -ERESTARTSYS;
}
return 0;
}
/*
* Split writes up in sane blocksizes to avoid
* denial-of-service type attacks
*/
static inline ssize_t do_tty_write(
ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
struct tty_struct *tty,
struct file *file,
const char __user *buf,
size_t count)
{
ssize_t ret, written = 0;
unsigned int chunk;
ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
if (ret < 0)
return ret;
/*
* We chunk up writes into a temporary buffer. This
* simplifies low-level drivers immensely, since they
* don't have locking issues and user mode accesses.
*
* But if TTY_NO_WRITE_SPLIT is set, we should use a
* big chunk-size..
*
* The default chunk-size is 2kB, because the NTTY
* layer has problems with bigger chunks. It will
* claim to be able to handle more characters than
* it actually does.
*
* FIXME: This can probably go away now except that 64K chunks
* are too likely to fail unless switched to vmalloc...
*/
chunk = 2048;
if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
chunk = 65536;
if (count < chunk)
chunk = count;
/* write_buf/write_cnt is protected by the atomic_write_lock mutex */
if (tty->write_cnt < chunk) {
unsigned char *buf_chunk;
if (chunk < 1024)
chunk = 1024;
buf_chunk = kmalloc(chunk, GFP_KERNEL);
if (!buf_chunk) {
ret = -ENOMEM;
goto out;
}
kfree(tty->write_buf);
tty->write_cnt = chunk;
tty->write_buf = buf_chunk;
}
/* Do the write .. */
for (;;) {
size_t size = count;
if (size > chunk)
size = chunk;
ret = -EFAULT;
if (copy_from_user(tty->write_buf, buf, size))
break;
ret = write(tty, file, tty->write_buf, size);
if (ret <= 0)
break;
written += ret;
buf += ret;
count -= ret;
if (!count)
break;
ret = -ERESTARTSYS;
if (signal_pending(current))
break;
cond_resched();
}
if (written) {
tty_update_time(&file_inode(file)->i_mtime);
ret = written;
}
out:
tty_write_unlock(tty);
return ret;
}
/**
* tty_write_message - write a message to a certain tty, not just the console.
* @tty: the destination tty_struct
* @msg: the message to write
*
* This is used for messages that need to be redirected to a specific tty.
* We don't put it into the syslog queue right now maybe in the future if
* really needed.
*
* We must still hold the BTM and test the CLOSING flag for the moment.
*/
void tty_write_message(struct tty_struct *tty, char *msg)
{
if (tty) {
mutex_lock(&tty->atomic_write_lock);
tty_lock(tty);
if (tty->ops->write && tty->count > 0)
tty->ops->write(tty, msg, strlen(msg));
tty_unlock(tty);
tty_write_unlock(tty);
}
return;
}
/**
* tty_write - write method for tty device file
* @file: tty file pointer
* @buf: user data to write
* @count: bytes to write
* @ppos: unused
*
* Write data to a tty device via the line discipline.
*
* Locking:
* Locks the line discipline as required
* Writes to the tty driver are serialized by the atomic_write_lock
* and are then processed in chunks to the device. The line discipline
n_tty: Fix loss of echoed characters and remove bkl from n_tty Fixes the loss of echoed (and other ldisc-generated characters) when the tty is stopped or when the driver output buffer is full (happens frequently for input during continuous program output, such as ^C) and removes the Big Kernel Lock from the N_TTY line discipline. Adds an "echo buffer" to the N_TTY line discipline that handles all ldisc-generated output (including echoed characters). Along with the loss of characters, this also fixes the associated loss of sync between tty output and the ldisc state when characters cannot be immediately written to the tty driver. The echo buffer stores (in addition to characters) state operations that need to be done at the time of character output (like management of the column position). This allows echo to cooperate correctly with program output, since the ldisc state remains consistent with actual characters written. Since the echo buffer code now isolates the tty column state code to the process_out* and process_echoes functions, we can remove the Big Kernel Lock (BKL) and replace it with mutex locks. Highlights are: * Handles echo (and other ldisc output) when tty driver buffer is full - continuous program output can block echo * Saves echo when tty is in stopped state (e.g. ^S) - (e.g.: ^Q will correctly cause held characters to be released for output) * Control character pairs (e.g. "^C") are treated atomically and not split up by interleaved program output * Line discipline state is kept consistent with characters sent to the tty driver * Remove the big kernel lock (BKL) from N_TTY line discipline Signed-off-by: Joe Peterson <joe@skyrush.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 13:40:53 +00:00
* write method will not be invoked in parallel for each device.
*/
static ssize_t tty_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
ssize_t ret;
if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
return -EIO;
if (!tty || !tty->ops->write || tty_io_error(tty))
return -EIO;
/* Short term debug to catch buggy drivers */
if (tty->ops->write_room == NULL)
tty_err(tty, "missing write_room method\n");
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_write(file, buf, count, ppos);
if (!ld->ops->write)
ret = -EIO;
else
ret = do_tty_write(ld->ops->write, tty, file, buf, count);
tty_ldisc_deref(ld);
return ret;
}
ssize_t redirected_tty_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct file *p = NULL;
spin_lock(&redirect_lock);
if (redirect)
p = get_file(redirect);
spin_unlock(&redirect_lock);
if (p) {
ssize_t res;
res = vfs_write(p, buf, count, &p->f_pos);
fput(p);
return res;
}
return tty_write(file, buf, count, ppos);
}
/**
* tty_send_xchar - send priority character
*
* Send a high priority character to the tty even if stopped
*
* Locking: none for xchar method, write ordering for write method.
*/
int tty_send_xchar(struct tty_struct *tty, char ch)
{
int was_stopped = tty->stopped;
if (tty->ops->send_xchar) {
down_read(&tty->termios_rwsem);
tty->ops->send_xchar(tty, ch);
up_read(&tty->termios_rwsem);
return 0;
}
if (tty_write_lock(tty, 0) < 0)
return -ERESTARTSYS;
down_read(&tty->termios_rwsem);
if (was_stopped)
start_tty(tty);
tty->ops->write(tty, &ch, 1);
if (was_stopped)
stop_tty(tty);
up_read(&tty->termios_rwsem);
tty_write_unlock(tty);
return 0;
}
static char ptychar[] = "pqrstuvwxyzabcde";
/**
* pty_line_name - generate name for a pty
* @driver: the tty driver in use
* @index: the minor number
* @p: output buffer of at least 6 bytes
*
* Generate a name from a driver reference and write it to the output
* buffer.
*
* Locking: None
*/
static void pty_line_name(struct tty_driver *driver, int index, char *p)
{
int i = index + driver->name_base;
/* ->name is initialized to "ttyp", but "tty" is expected */
sprintf(p, "%s%c%x",
driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
ptychar[i >> 4 & 0xf], i & 0xf);
}
/**
* tty_line_name - generate name for a tty
* @driver: the tty driver in use
* @index: the minor number
* @p: output buffer of at least 7 bytes
*
* Generate a name from a driver reference and write it to the output
* buffer.
*
* Locking: None
*/
static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
{
if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
return sprintf(p, "%s", driver->name);
else
return sprintf(p, "%s%d", driver->name,
index + driver->name_base);
}
/**
* tty_driver_lookup_tty() - find an existing tty, if any
* @driver: the driver for the tty
* @idx: the minor number
*
* Return the tty, if found. If not found, return NULL or ERR_PTR() if the
* driver lookup() method returns an error.
*
* Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
*/
static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 03:04:08 +00:00
struct file *file, int idx)
{
struct tty_struct *tty;
if (driver->ops->lookup)
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 03:04:08 +00:00
tty = driver->ops->lookup(driver, file, idx);
else
tty = driver->ttys[idx];
if (!IS_ERR(tty))
tty_kref_get(tty);
return tty;
}
/**
* tty_init_termios - helper for termios setup
* @tty: the tty to set up
*
* Initialise the termios structures for this tty. Thus runs under
* the tty_mutex currently so we can be relaxed about ordering.
*/
void tty_init_termios(struct tty_struct *tty)
{
struct ktermios *tp;
int idx = tty->index;
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
tty->termios = tty->driver->init_termios;
else {
/* Check for lazy saved data */
tp = tty->driver->termios[idx];
if (tp != NULL) {
tty->termios = *tp;
tty->termios.c_line = tty->driver->init_termios.c_line;
} else
tty->termios = tty->driver->init_termios;
}
/* Compatibility until drivers always set this */
tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
}
EXPORT_SYMBOL_GPL(tty_init_termios);
int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
{
tty_init_termios(tty);
tty_driver_kref_get(driver);
tty->count++;
driver->ttys[tty->index] = tty;
return 0;
}
EXPORT_SYMBOL_GPL(tty_standard_install);
/**
* tty_driver_install_tty() - install a tty entry in the driver
* @driver: the driver for the tty
* @tty: the tty
*
* Install a tty object into the driver tables. The tty->index field
* will be set by the time this is called. This method is responsible
* for ensuring any need additional structures are allocated and
* configured.
*
* Locking: tty_mutex for now
*/
static int tty_driver_install_tty(struct tty_driver *driver,
struct tty_struct *tty)
{
return driver->ops->install ? driver->ops->install(driver, tty) :
tty_standard_install(driver, tty);
}
/**
* tty_driver_remove_tty() - remove a tty from the driver tables
* @driver: the driver for the tty
* @idx: the minor number
*
* Remvoe a tty object from the driver tables. The tty->index field
* will be set by the time this is called.
*
* Locking: tty_mutex for now
*/
static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
{
if (driver->ops->remove)
driver->ops->remove(driver, tty);
else
driver->ttys[tty->index] = NULL;
}
/*
* tty_reopen() - fast re-open of an open tty
* @tty - the tty to open
*
* Return 0 on success, -errno on error.
tty: Clarify re-open behavior of master ptys Re-opening master ptys is not allowed. Once opened and for the remaining lifetime of the master pty, its tty count is 1. If its tty count has dropped to 0, then the master pty was closed and TTY_CLOSING was set, and destruction may begin imminently. Besides the normal case of a legacy BSD pty master being re-opened (which always returns -EIO), this code is only reachable in 2 degenerate cases: 1. The pty master is the controlling terminal (this is possible through the TIOCSCTTY ioctl). pty masters are not designed to be controlling terminals and it's an oversight that tiocsctty() ever let that happen. The attempted open of /dev/tty will always fail. No known program does this. 2. The legacy BSD pty slave was opened first. The slave open will fail in pty_open() and tty_release() will commence. But before tty_release() claims the tty_mutex, there is a very small window where a parallel master open might succeed. In a test of racing legacy BSD slave and master parallel opens, where: slave open attempts: 10000 success:4527 failure:5473 master open attempts: 11728 success:5789 failure:5939 only 8 master open attempts would have succeeded reaching this code and successfully opened the master pty. This case is not possible with SysV ptys. Always return -EIO if a master pty is re-opened or the slave is opened first and the master opened in parallel (for legacy BSD ptys). Furthermore, now that changing the slave's count is not required, the tty_lock is sufficient for preventing concurrent changes to the tty being re-opened (or failing re-opening). Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:47 +00:00
* Re-opens on master ptys are not allowed and return -EIO.
*
tty: Clarify re-open behavior of master ptys Re-opening master ptys is not allowed. Once opened and for the remaining lifetime of the master pty, its tty count is 1. If its tty count has dropped to 0, then the master pty was closed and TTY_CLOSING was set, and destruction may begin imminently. Besides the normal case of a legacy BSD pty master being re-opened (which always returns -EIO), this code is only reachable in 2 degenerate cases: 1. The pty master is the controlling terminal (this is possible through the TIOCSCTTY ioctl). pty masters are not designed to be controlling terminals and it's an oversight that tiocsctty() ever let that happen. The attempted open of /dev/tty will always fail. No known program does this. 2. The legacy BSD pty slave was opened first. The slave open will fail in pty_open() and tty_release() will commence. But before tty_release() claims the tty_mutex, there is a very small window where a parallel master open might succeed. In a test of racing legacy BSD slave and master parallel opens, where: slave open attempts: 10000 success:4527 failure:5473 master open attempts: 11728 success:5789 failure:5939 only 8 master open attempts would have succeeded reaching this code and successfully opened the master pty. This case is not possible with SysV ptys. Always return -EIO if a master pty is re-opened or the slave is opened first and the master opened in parallel (for legacy BSD ptys). Furthermore, now that changing the slave's count is not required, the tty_lock is sufficient for preventing concurrent changes to the tty being re-opened (or failing re-opening). Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:47 +00:00
* Locking: Caller must hold tty_lock
*/
static int tty_reopen(struct tty_struct *tty)
{
struct tty_driver *driver = tty->driver;
if (driver->type == TTY_DRIVER_TYPE_PTY &&
tty: Clarify re-open behavior of master ptys Re-opening master ptys is not allowed. Once opened and for the remaining lifetime of the master pty, its tty count is 1. If its tty count has dropped to 0, then the master pty was closed and TTY_CLOSING was set, and destruction may begin imminently. Besides the normal case of a legacy BSD pty master being re-opened (which always returns -EIO), this code is only reachable in 2 degenerate cases: 1. The pty master is the controlling terminal (this is possible through the TIOCSCTTY ioctl). pty masters are not designed to be controlling terminals and it's an oversight that tiocsctty() ever let that happen. The attempted open of /dev/tty will always fail. No known program does this. 2. The legacy BSD pty slave was opened first. The slave open will fail in pty_open() and tty_release() will commence. But before tty_release() claims the tty_mutex, there is a very small window where a parallel master open might succeed. In a test of racing legacy BSD slave and master parallel opens, where: slave open attempts: 10000 success:4527 failure:5473 master open attempts: 11728 success:5789 failure:5939 only 8 master open attempts would have succeeded reaching this code and successfully opened the master pty. This case is not possible with SysV ptys. Always return -EIO if a master pty is re-opened or the slave is opened first and the master opened in parallel (for legacy BSD ptys). Furthermore, now that changing the slave's count is not required, the tty_lock is sufficient for preventing concurrent changes to the tty being re-opened (or failing re-opening). Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:47 +00:00
driver->subtype == PTY_TYPE_MASTER)
return -EIO;
if (!tty->count)
return -EAGAIN;
if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
return -EBUSY;
tty->count++;
tty: Destroy ldisc instance on hangup Currently, when the tty is hungup, the ldisc is re-instanced; ie., the current instance is destroyed and a new instance is created. The purpose of this design was to guarantee a valid, open ldisc for the lifetime of the tty. However, now that tty buffers are owned by and have lifetime equivalent to the tty_port (since v3.10), any data received immediately after the ldisc is re-instanced may cause continued driver i/o operations concurrently with the driver's hangup() operation. For drivers that shutdown h/w on hangup, this is unexpected and usually bad. For example, the serial core may free the xmit buffer page concurrently with an in-progress write() operation (triggered by echo). With the existing stable and robust ldisc reference handling, the cleaned-up tty_reopen(), the straggling unsafe ldisc use cleaned up, and the preparation to properly handle a NULL tty->ldisc, the ldisc instance can be destroyed and only re-instanced when the tty is re-opened. If the tty was opened as /dev/console or /dev/tty0, the original behavior of re-instancing the ldisc is retained (the 'reinit' parameter to tty_ldisc_hangup() is true). This is required since those file descriptors are never hungup. This patch has neglible impact on userspace; the tty file_operations ptr is changed to point to the hungup file operations _before_ the ldisc instance is destroyed, so only racing file operations might now retrieve a NULL ldisc reference (which is simply handled as if the hungup file operation had been called instead -- see "tty: Prepare for destroying line discipline on hangup"). This resolves a long-standing FIXME and several crash reports. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-11 06:41:06 +00:00
if (!tty->ldisc)
return tty_ldisc_reinit(tty, tty->termios.c_line);
return 0;
}
/**
* tty_init_dev - initialise a tty device
* @driver: tty driver we are opening a device on
* @idx: device index
* @ret_tty: returned tty structure
*
* Prepare a tty device. This may not be a "new" clean device but
* could also be an active device. The pty drivers require special
* handling because of this.
*
* Locking:
* The function is called under the tty_mutex, which
* protects us from the tty struct or driver itself going away.
*
* On exit the tty device has the line discipline attached and
* a reference count of 1. If a pair was created for pty/tty use
* and the other was a pty master then it too has a reference count of 1.
*
* WSH 06/09/97: Rewritten to remove races and properly clean up after a
* failed open. The new code protects the open with a mutex, so it's
* really quite straightforward. The mutex locking can probably be
* relaxed for the (most common) case of reopening a tty.
*/
struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;
int retval;
/*
* First time open is complex, especially for PTY devices.
* This code guarantees that either everything succeeds and the
* TTY is ready for operation, or else the table slots are vacated
* and the allocated memory released. (Except that the termios
* and locked termios may be retained.)
*/
if (!try_module_get(driver->owner))
return ERR_PTR(-ENODEV);
tty = alloc_tty_struct(driver, idx);
if (!tty) {
retval = -ENOMEM;
goto err_module_put;
}
tty_lock(tty);
retval = tty_driver_install_tty(driver, tty);
if (retval < 0)
goto err_free_tty;
if (!tty->port)
tty->port = driver->ports[idx];
WARN_RATELIMIT(!tty->port,
"%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
__func__, tty->driver->name);
tty->port->itty = tty;
/*
* Structures all installed ... call the ldisc open routines.
* If we fail here just call release_tty to clean up. No need
* to decrement the use counts, as release_tty doesn't care.
*/
retval = tty_ldisc_setup(tty, tty->link);
if (retval)
goto err_release_tty;
/* Return the tty locked so that it cannot vanish under the caller */
return tty;
err_free_tty:
tty_unlock(tty);
free_tty_struct(tty);
err_module_put:
module_put(driver->owner);
return ERR_PTR(retval);
/* call the tty release_tty routine to clean out this slot */
err_release_tty:
tty_unlock(tty);
tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
retval, idx);
release_tty(tty, idx);
return ERR_PTR(retval);
}
static void tty_free_termios(struct tty_struct *tty)
{
struct ktermios *tp;
int idx = tty->index;
/* If the port is going to reset then it has no termios to save */
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
return;
/* Stash the termios data */
tp = tty->driver->termios[idx];
if (tp == NULL) {
tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
if (tp == NULL)
return;
tty->driver->termios[idx] = tp;
}
*tp = tty->termios;
}
/**
* tty_flush_works - flush all works of a tty/pty pair
* @tty: tty device to flush works for (or either end of a pty pair)
*
* Sync flush all works belonging to @tty (and the 'other' tty).
*/
static void tty_flush_works(struct tty_struct *tty)
{
flush_work(&tty->SAK_work);
flush_work(&tty->hangup_work);
if (tty->link) {
flush_work(&tty->link->SAK_work);
flush_work(&tty->link->hangup_work);
}
}
/**
* release_one_tty - release tty structure memory
* @kref: kref of tty we are obliterating
*
* Releases memory associated with a tty structure, and clears out the
* driver table slots. This function is called when a device is no longer
* in use. It also gets called when setup of a device fails.
*
* Locking:
* takes the file list lock internally when working on the list
* of ttys that the driver keeps.
*
* This method gets called from a work queue so that the driver private
tty: Fix regressions caused by commit b50989dc The following commit made console open fails while booting: commit b50989dc444599c8b21edc23536fc305f4e9b7d5 Author: Alan Cox <alan@linux.intel.com> Date: Sat Sep 19 13:13:22 2009 -0700 tty: make the kref destructor occur asynchronously Due to tty release routines run in a workqueue now, error like the following will be reported while booting: INIT open /dev/console Input/output error It also causes hibernation regression to appear as reported at http://bugzilla.kernel.org/show_bug.cgi?id=14229 The reason is that now there's latency issue with closing, but when we open a "closing not finished" tty, -EIO will be returned. Fix it as per the following Alan's suggestion: Fun but it's actually not a bug and the fix is wrong in itself as the port may be closing but not yet being destructed, in which case it seems to do the wrong thing. Opening a tty that is closing (and could be closing for long periods) is supposed to return -EIO. I suspect a better way to deal with this and keep the old console timing is to split tty->shutdown into two functions. tty->shutdown() - called synchronously just before we dump the tty onto the waitqueue for destruction tty->cleanup() - called when the destructor runs. We would then do the shutdown part which can occur in IRQ context fine, before queueing the rest of the release (from tty->magic = 0 ... the end) to occur asynchronously The USB update in -next would then need a call like if (tty->cleanup) tty->cleanup(tty); at the top of the async function and the USB shutdown to be split between shutdown and cleanup as the USB resource cleanup and final tidy cannot occur synchronously as it needs to sleep. In other words the logic becomes final kref put make object unfindable async clean it up Signed-off-by: Dave Young <hidave.darkstar@gmail.com> [ rjw: Rebased on top of 2.6.31-git, reworked the changelog. ] Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl> [ Changed serial naming to match new rules, dropped tty_shutdown as per comments from Alan Stern - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-27 16:00:42 +00:00
* cleanup ops can sleep (needed for USB at least)
*/
static void release_one_tty(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, hangup_work);
struct tty_driver *driver = tty->driver;
tty: Fix potential use after free in release_one_tty In case if we're releasing the last tty reference the following call sequence is possible tty_driver_kref_put destruct_tty_driver kfree(driver); where @driver is used in next module_put call, which leads to | [ 285.964007] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 | [ 285.964007] Workqueue: events release_one_tty | [ 285.964007] task: ffff8800cc7ea5f0 ti: ffff8800cb800000 task.ti: ffff8800cb800000 | [ 285.964007] RIP: 0010:[<ffffffff810aeaf5>] [<ffffffff810aeaf5>] module_put+0x24/0xf4 | [ 285.964007] RSP: 0018:ffff8800cb801d48 EFLAGS: 00010213 | [ 285.964007] RAX: ffff8800cb801fd8 RBX: ffff8800ca3429d0 RCX: ffff8800cb1db400 | [ 285.964007] RDX: 0000000000000000 RSI: ffffffff817349c1 RDI: 0000000000000001 | [ 285.964007] RBP: ffff8800cb801d60 R08: ffff8800cd632b40 R09: 0000000000000000 | [ 285.964007] R10: 00000000ffffffff R11: ffff88011f40a000 R12: 6b6b6b6b6b6b6b6b | [ 285.964007] R13: ffff8800ca342520 R14: 0000000000000000 R15: ffff88011f5d8200 | [ 285.964007] FS: 0000000000000000(0000) GS:ffff88011f400000(0000) knlGS:0000000000000000 | [ 285.964007] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b | [ 285.964007] CR2: 00007faf5229d090 CR3: 0000000001c0b000 CR4: 00000000000006f0 | [ 285.964007] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 | [ 285.964007] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 | [ 285.964007] Stack: | [ 285.964007] ffff8800ca3429d0 ffff8800ca342a30 ffff8800ca342520 ffff8800cb801d88 | [ 285.964007] ffffffff8146554a ffff8800cc77cc78 ffff8800ca3429d0 ffff88011f5d3800 | [ 285.964007] ffff8800cb801e08 ffffffff810683c1 ffffffff810682ff 0000000000000046 | [ 285.964007] Call Trace: | [ 285.964007] [<ffffffff8146554a>] release_one_tty+0x54/0xa3 | [ 285.964007] [<ffffffff810683c1>] process_one_work+0x223/0x404 | [ 285.964007] [<ffffffff810682ff>] ? process_one_work+0x161/0x404 | [ 285.964007] [<ffffffff81068971>] worker_thread+0x136/0x205 | [ 285.964007] [<ffffffff8106883b>] ? rescuer_thread+0x26a/0x26a | [ 285.964007] [<ffffffff8106e5bf>] kthread+0xa2/0xaa | [ 285.964007] [<ffffffff810a4586>] ? trace_hardirqs_on_caller+0x16/0x1eb | [ 285.964007] [<ffffffff8106e51d>] ? __kthread_parkme+0x65/0x65 | [ 285.964007] [<ffffffff8173f59c>] ret_from_fork+0x7c/0xb0 | [ 285.964007] [<ffffffff8106e51d>] ? __kthread_parkme+0x65/0x65 | [ 285.964007] Code: 09 00 5b 41 5c 5d c3 0f 1f 44 00 00 55 48 85 ff 48 89 e5 41 55 41 54 49 89 fc 53 0f 84 d3 00 | 00 00 bf 01 00 00 00 e8 d0 a1 fc ff <49> 8b 84 24 50 02 00 00 65 48 ff 40 08 4c 8b 6d 08 0f 1f 44 00 so simply keep a local reference to the module owner and use it later. CC: Pavel Emelyanov <xemul@parallels.com> CC: Jiri Slaby <jslaby@suse.cz> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-08-07 20:26:15 +00:00
struct module *owner = driver->owner;
tty: Fix regressions caused by commit b50989dc The following commit made console open fails while booting: commit b50989dc444599c8b21edc23536fc305f4e9b7d5 Author: Alan Cox <alan@linux.intel.com> Date: Sat Sep 19 13:13:22 2009 -0700 tty: make the kref destructor occur asynchronously Due to tty release routines run in a workqueue now, error like the following will be reported while booting: INIT open /dev/console Input/output error It also causes hibernation regression to appear as reported at http://bugzilla.kernel.org/show_bug.cgi?id=14229 The reason is that now there's latency issue with closing, but when we open a "closing not finished" tty, -EIO will be returned. Fix it as per the following Alan's suggestion: Fun but it's actually not a bug and the fix is wrong in itself as the port may be closing but not yet being destructed, in which case it seems to do the wrong thing. Opening a tty that is closing (and could be closing for long periods) is supposed to return -EIO. I suspect a better way to deal with this and keep the old console timing is to split tty->shutdown into two functions. tty->shutdown() - called synchronously just before we dump the tty onto the waitqueue for destruction tty->cleanup() - called when the destructor runs. We would then do the shutdown part which can occur in IRQ context fine, before queueing the rest of the release (from tty->magic = 0 ... the end) to occur asynchronously The USB update in -next would then need a call like if (tty->cleanup) tty->cleanup(tty); at the top of the async function and the USB shutdown to be split between shutdown and cleanup as the USB resource cleanup and final tidy cannot occur synchronously as it needs to sleep. In other words the logic becomes final kref put make object unfindable async clean it up Signed-off-by: Dave Young <hidave.darkstar@gmail.com> [ rjw: Rebased on top of 2.6.31-git, reworked the changelog. ] Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl> [ Changed serial naming to match new rules, dropped tty_shutdown as per comments from Alan Stern - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-27 16:00:42 +00:00
if (tty->ops->cleanup)
tty->ops->cleanup(tty);
tty->magic = 0;
tty_driver_kref_put(driver);
tty: Fix potential use after free in release_one_tty In case if we're releasing the last tty reference the following call sequence is possible tty_driver_kref_put destruct_tty_driver kfree(driver); where @driver is used in next module_put call, which leads to | [ 285.964007] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 | [ 285.964007] Workqueue: events release_one_tty | [ 285.964007] task: ffff8800cc7ea5f0 ti: ffff8800cb800000 task.ti: ffff8800cb800000 | [ 285.964007] RIP: 0010:[<ffffffff810aeaf5>] [<ffffffff810aeaf5>] module_put+0x24/0xf4 | [ 285.964007] RSP: 0018:ffff8800cb801d48 EFLAGS: 00010213 | [ 285.964007] RAX: ffff8800cb801fd8 RBX: ffff8800ca3429d0 RCX: ffff8800cb1db400 | [ 285.964007] RDX: 0000000000000000 RSI: ffffffff817349c1 RDI: 0000000000000001 | [ 285.964007] RBP: ffff8800cb801d60 R08: ffff8800cd632b40 R09: 0000000000000000 | [ 285.964007] R10: 00000000ffffffff R11: ffff88011f40a000 R12: 6b6b6b6b6b6b6b6b | [ 285.964007] R13: ffff8800ca342520 R14: 0000000000000000 R15: ffff88011f5d8200 | [ 285.964007] FS: 0000000000000000(0000) GS:ffff88011f400000(0000) knlGS:0000000000000000 | [ 285.964007] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b | [ 285.964007] CR2: 00007faf5229d090 CR3: 0000000001c0b000 CR4: 00000000000006f0 | [ 285.964007] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 | [ 285.964007] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 | [ 285.964007] Stack: | [ 285.964007] ffff8800ca3429d0 ffff8800ca342a30 ffff8800ca342520 ffff8800cb801d88 | [ 285.964007] ffffffff8146554a ffff8800cc77cc78 ffff8800ca3429d0 ffff88011f5d3800 | [ 285.964007] ffff8800cb801e08 ffffffff810683c1 ffffffff810682ff 0000000000000046 | [ 285.964007] Call Trace: | [ 285.964007] [<ffffffff8146554a>] release_one_tty+0x54/0xa3 | [ 285.964007] [<ffffffff810683c1>] process_one_work+0x223/0x404 | [ 285.964007] [<ffffffff810682ff>] ? process_one_work+0x161/0x404 | [ 285.964007] [<ffffffff81068971>] worker_thread+0x136/0x205 | [ 285.964007] [<ffffffff8106883b>] ? rescuer_thread+0x26a/0x26a | [ 285.964007] [<ffffffff8106e5bf>] kthread+0xa2/0xaa | [ 285.964007] [<ffffffff810a4586>] ? trace_hardirqs_on_caller+0x16/0x1eb | [ 285.964007] [<ffffffff8106e51d>] ? __kthread_parkme+0x65/0x65 | [ 285.964007] [<ffffffff8173f59c>] ret_from_fork+0x7c/0xb0 | [ 285.964007] [<ffffffff8106e51d>] ? __kthread_parkme+0x65/0x65 | [ 285.964007] Code: 09 00 5b 41 5c 5d c3 0f 1f 44 00 00 55 48 85 ff 48 89 e5 41 55 41 54 49 89 fc 53 0f 84 d3 00 | 00 00 bf 01 00 00 00 e8 d0 a1 fc ff <49> 8b 84 24 50 02 00 00 65 48 ff 40 08 4c 8b 6d 08 0f 1f 44 00 so simply keep a local reference to the module owner and use it later. CC: Pavel Emelyanov <xemul@parallels.com> CC: Jiri Slaby <jslaby@suse.cz> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-08-07 20:26:15 +00:00
module_put(owner);
spin_lock(&tty->files_lock);
list_del_init(&tty->tty_files);
spin_unlock(&tty->files_lock);
put_pid(tty->pgrp);
put_pid(tty->session);
free_tty_struct(tty);
}
static void queue_release_one_tty(struct kref *kref)
{
struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
tty: Fix regressions caused by commit b50989dc The following commit made console open fails while booting: commit b50989dc444599c8b21edc23536fc305f4e9b7d5 Author: Alan Cox <alan@linux.intel.com> Date: Sat Sep 19 13:13:22 2009 -0700 tty: make the kref destructor occur asynchronously Due to tty release routines run in a workqueue now, error like the following will be reported while booting: INIT open /dev/console Input/output error It also causes hibernation regression to appear as reported at http://bugzilla.kernel.org/show_bug.cgi?id=14229 The reason is that now there's latency issue with closing, but when we open a "closing not finished" tty, -EIO will be returned. Fix it as per the following Alan's suggestion: Fun but it's actually not a bug and the fix is wrong in itself as the port may be closing but not yet being destructed, in which case it seems to do the wrong thing. Opening a tty that is closing (and could be closing for long periods) is supposed to return -EIO. I suspect a better way to deal with this and keep the old console timing is to split tty->shutdown into two functions. tty->shutdown() - called synchronously just before we dump the tty onto the waitqueue for destruction tty->cleanup() - called when the destructor runs. We would then do the shutdown part which can occur in IRQ context fine, before queueing the rest of the release (from tty->magic = 0 ... the end) to occur asynchronously The USB update in -next would then need a call like if (tty->cleanup) tty->cleanup(tty); at the top of the async function and the USB shutdown to be split between shutdown and cleanup as the USB resource cleanup and final tidy cannot occur synchronously as it needs to sleep. In other words the logic becomes final kref put make object unfindable async clean it up Signed-off-by: Dave Young <hidave.darkstar@gmail.com> [ rjw: Rebased on top of 2.6.31-git, reworked the changelog. ] Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl> [ Changed serial naming to match new rules, dropped tty_shutdown as per comments from Alan Stern - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-27 16:00:42 +00:00
/* The hangup queue is now free so we can reuse it rather than
waste a chunk of memory for each port */
INIT_WORK(&tty->hangup_work, release_one_tty);
schedule_work(&tty->hangup_work);
}
/**
* tty_kref_put - release a tty kref
* @tty: tty device
*
* Release a reference to a tty device and if need be let the kref
* layer destruct the object for us
*/
void tty_kref_put(struct tty_struct *tty)
{
if (tty)
kref_put(&tty->kref, queue_release_one_tty);
}
EXPORT_SYMBOL(tty_kref_put);
/**
* release_tty - release tty structure memory
*
* Release both @tty and a possible linked partner (think pty pair),
* and decrement the refcount of the backing module.
*
* Locking:
* tty_mutex
* takes the file list lock internally when working on the list
* of ttys that the driver keeps.
*
*/
static void release_tty(struct tty_struct *tty, int idx)
{
/* This should always be true but check for the moment */
WARN_ON(tty->index != idx);
WARN_ON(!mutex_is_locked(&tty_mutex));
if (tty->ops->shutdown)
tty->ops->shutdown(tty);
tty_free_termios(tty);
tty_driver_remove_tty(tty->driver, tty);
tty->port->itty = NULL;
if (tty->link)
tty->link->port->itty = NULL;
tty_buffer_cancel_work(tty->port);
tty_kref_put(tty->link);
tty_kref_put(tty);
}
/**
* tty_release_checks - check a tty before real release
* @tty: tty to check
* @o_tty: link of @tty (if any)
* @idx: index of the tty
*
* Performs some paranoid checking before true release of the @tty.
* This is a no-op unless TTY_PARANOIA_CHECK is defined.
*/
static int tty_release_checks(struct tty_struct *tty, int idx)
{
#ifdef TTY_PARANOIA_CHECK
if (idx < 0 || idx >= tty->driver->num) {
tty_debug(tty, "bad idx %d\n", idx);
return -1;
}
/* not much to check for devpts */
if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
return 0;
if (tty != tty->driver->ttys[idx]) {
tty_debug(tty, "bad driver table[%d] = %p\n",
idx, tty->driver->ttys[idx]);
return -1;
}
if (tty->driver->other) {
struct tty_struct *o_tty = tty->link;
if (o_tty != tty->driver->other->ttys[idx]) {
tty_debug(tty, "bad other table[%d] = %p\n",
idx, tty->driver->other->ttys[idx]);
return -1;
}
if (o_tty->link != tty) {
tty_debug(tty, "bad link = %p\n", o_tty->link);
return -1;
}
}
#endif
return 0;
}
/**
* tty_release_struct - release a tty struct
* @tty: tty device
* @idx: index of the tty
*
* Performs the final steps to release and free a tty device. It is
* roughly the reverse of tty_init_dev.
*/
void tty_release_struct(struct tty_struct *tty, int idx)
{
/*
* Ask the line discipline code to release its structures
*/
tty_ldisc_release(tty);
/* Wait for pending work before tty destruction commmences */
tty_flush_works(tty);
tty_debug_hangup(tty, "freeing structure\n");
/*
* The release_tty function takes care of the details of clearing
* the slots and preserving the termios structure. The tty_unlock_pair
* should be safe as we keep a kref while the tty is locked (so the
* unlock never unlocks a freed tty).
*/
mutex_lock(&tty_mutex);
release_tty(tty, idx);
mutex_unlock(&tty_mutex);
}
EXPORT_SYMBOL_GPL(tty_release_struct);
/**
* tty_release - vfs callback for close
* @inode: inode of tty
* @filp: file pointer for handle to tty
*
* Called the last time each file handle is closed that references
* this tty. There may however be several such references.
*
* Locking:
* Takes bkl. See tty_release_dev
*
* Even releasing the tty structures is a tricky business.. We have
* to be very careful that the structures are all released at the
* same time, as interrupts might otherwise get the wrong pointers.
*
* WSH 09/09/97: rewritten to avoid some nasty race conditions that could
* lead to double frees or releasing memory still in use.
*/
int tty_release(struct inode *inode, struct file *filp)
{
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_struct *tty = file_tty(filp);
struct tty_struct *o_tty = NULL;
int do_sleep, final;
int idx;
long timeout = 0;
int once = 1;
if (tty_paranoia_check(tty, inode, __func__))
return 0;
tty_lock(tty);
check_tty_count(tty, __func__);
__tty_fasync(-1, filp, 0);
idx = tty->index;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
o_tty = tty->link;
if (tty_release_checks(tty, idx)) {
tty_unlock(tty);
return 0;
}
tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
if (tty->ops->close)
tty->ops->close(tty, filp);
/* If tty is pty master, lock the slave pty (stable lock order) */
tty_lock_slave(o_tty);
/*
* Sanity check: if tty->count is going to zero, there shouldn't be
* any waiters on tty->read_wait or tty->write_wait. We test the
* wait queues and kick everyone out _before_ actually starting to
* close. This ensures that we won't block while releasing the tty
* structure.
*
* The test for the o_tty closing is necessary, since the master and
* slave sides may close in any order. If the slave side closes out
* first, its count will be one, since the master side holds an open.
* Thus this test wouldn't be triggered at the time the slave closed,
* so we do it now.
*/
while (1) {
do_sleep = 0;
if (tty->count <= 1) {
if (waitqueue_active(&tty->read_wait)) {
wake_up_poll(&tty->read_wait, POLLIN);
do_sleep++;
}
if (waitqueue_active(&tty->write_wait)) {
wake_up_poll(&tty->write_wait, POLLOUT);
do_sleep++;
}
}
if (o_tty && o_tty->count <= 1) {
if (waitqueue_active(&o_tty->read_wait)) {
wake_up_poll(&o_tty->read_wait, POLLIN);
do_sleep++;
}
if (waitqueue_active(&o_tty->write_wait)) {
wake_up_poll(&o_tty->write_wait, POLLOUT);
do_sleep++;
}
}
if (!do_sleep)
break;
if (once) {
once = 0;
tty_warn(tty, "read/write wait queue active!\n");
}
schedule_timeout_killable(timeout);
if (timeout < 120 * HZ)
timeout = 2 * timeout + 1;
else
timeout = MAX_SCHEDULE_TIMEOUT;
}
if (o_tty) {
if (--o_tty->count < 0) {
tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
o_tty->count = 0;
}
}
if (--tty->count < 0) {
tty_warn(tty, "bad tty->count (%d)\n", tty->count);
tty->count = 0;
}
/*
* We've decremented tty->count, so we need to remove this file
* descriptor off the tty->tty_files list; this serves two
* purposes:
* - check_tty_count sees the correct number of file descriptors
* associated with this tty.
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
tty_del_file(filp);
/*
* Perform some housekeeping before deciding whether to return.
*
* If _either_ side is closing, make sure there aren't any
* processes that still think tty or o_tty is their controlling
* tty.
*/
if (!tty->count) {
read_lock(&tasklist_lock);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
session_clear_tty(tty->session);
if (o_tty)
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
session_clear_tty(o_tty->session);
read_unlock(&tasklist_lock);
}
/* check whether both sides are closing ... */
final = !tty->count && !(o_tty && o_tty->count);
tty_unlock_slave(o_tty);
tty_unlock(tty);
/* At this point, the tty->count == 0 should ensure a dead tty
cannot be re-opened by a racing opener */
if (!final)
return 0;
tty_debug_hangup(tty, "final close\n");
tty_release_struct(tty, idx);
return 0;
}
/**
tty: Re-open /dev/tty without tty_mutex Opening /dev/tty (ie., the controlling tty for the current task) is always a re-open of the underlying tty. Because holding the tty_lock is sufficient for safely re-opening a tty, and because having a tty kref is sufficient for safely acquiring the tty_lock [1], tty_open_current_tty() does not require holding tty_mutex. Repurpose tty_open_current_tty() to perform the re-open itself and refactor tty_open(). [1] Analysis of safely re-opening the current tty w/o tty_mutex get_current_tty() gets a tty kref from the already kref'ed tty value of current->signal->tty while holding the sighand lock for the current task. This guarantees that the tty pointer returned from get_current_tty() points to a tty which remains referenceable while holding the kref. Although release_tty() may run concurrently, and thus the driver reference may be removed, release_one_tty() cannot have run, and won't while holding the tty kref. This, in turn, guarantees the tty_lock() can safely be acquired (since tty->magic and tty->legacy_mutex are still a valid dereferences). The tty_lock() also gets a tty kref to prevent the tty_unlock() from dereferencing a released tty. Thus, the kref returned from get_current_tty() can be released. Lastly, the first operation of tty_reopen() is to check the tty count. If non-zero, this ensures release_tty() is not running concurrently, and the driver references have not been removed. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:50 +00:00
* tty_open_current_tty - get locked tty of current task
* @device: device number
* @filp: file pointer to tty
tty: Re-open /dev/tty without tty_mutex Opening /dev/tty (ie., the controlling tty for the current task) is always a re-open of the underlying tty. Because holding the tty_lock is sufficient for safely re-opening a tty, and because having a tty kref is sufficient for safely acquiring the tty_lock [1], tty_open_current_tty() does not require holding tty_mutex. Repurpose tty_open_current_tty() to perform the re-open itself and refactor tty_open(). [1] Analysis of safely re-opening the current tty w/o tty_mutex get_current_tty() gets a tty kref from the already kref'ed tty value of current->signal->tty while holding the sighand lock for the current task. This guarantees that the tty pointer returned from get_current_tty() points to a tty which remains referenceable while holding the kref. Although release_tty() may run concurrently, and thus the driver reference may be removed, release_one_tty() cannot have run, and won't while holding the tty kref. This, in turn, guarantees the tty_lock() can safely be acquired (since tty->magic and tty->legacy_mutex are still a valid dereferences). The tty_lock() also gets a tty kref to prevent the tty_unlock() from dereferencing a released tty. Thus, the kref returned from get_current_tty() can be released. Lastly, the first operation of tty_reopen() is to check the tty count. If non-zero, this ensures release_tty() is not running concurrently, and the driver references have not been removed. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:50 +00:00
* @return: locked tty of the current task iff @device is /dev/tty
*
* Performs a re-open of the current task's controlling tty.
*
* We cannot return driver and index like for the other nodes because
* devpts will not work then. It expects inodes to be from devpts FS.
*/
static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
{
struct tty_struct *tty;
tty: Re-open /dev/tty without tty_mutex Opening /dev/tty (ie., the controlling tty for the current task) is always a re-open of the underlying tty. Because holding the tty_lock is sufficient for safely re-opening a tty, and because having a tty kref is sufficient for safely acquiring the tty_lock [1], tty_open_current_tty() does not require holding tty_mutex. Repurpose tty_open_current_tty() to perform the re-open itself and refactor tty_open(). [1] Analysis of safely re-opening the current tty w/o tty_mutex get_current_tty() gets a tty kref from the already kref'ed tty value of current->signal->tty while holding the sighand lock for the current task. This guarantees that the tty pointer returned from get_current_tty() points to a tty which remains referenceable while holding the kref. Although release_tty() may run concurrently, and thus the driver reference may be removed, release_one_tty() cannot have run, and won't while holding the tty kref. This, in turn, guarantees the tty_lock() can safely be acquired (since tty->magic and tty->legacy_mutex are still a valid dereferences). The tty_lock() also gets a tty kref to prevent the tty_unlock() from dereferencing a released tty. Thus, the kref returned from get_current_tty() can be released. Lastly, the first operation of tty_reopen() is to check the tty count. If non-zero, this ensures release_tty() is not running concurrently, and the driver references have not been removed. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:50 +00:00
int retval;
if (device != MKDEV(TTYAUX_MAJOR, 0))
return NULL;
tty = get_current_tty();
if (!tty)
return ERR_PTR(-ENXIO);
filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
/* noctty = 1; */
tty: Re-open /dev/tty without tty_mutex Opening /dev/tty (ie., the controlling tty for the current task) is always a re-open of the underlying tty. Because holding the tty_lock is sufficient for safely re-opening a tty, and because having a tty kref is sufficient for safely acquiring the tty_lock [1], tty_open_current_tty() does not require holding tty_mutex. Repurpose tty_open_current_tty() to perform the re-open itself and refactor tty_open(). [1] Analysis of safely re-opening the current tty w/o tty_mutex get_current_tty() gets a tty kref from the already kref'ed tty value of current->signal->tty while holding the sighand lock for the current task. This guarantees that the tty pointer returned from get_current_tty() points to a tty which remains referenceable while holding the kref. Although release_tty() may run concurrently, and thus the driver reference may be removed, release_one_tty() cannot have run, and won't while holding the tty kref. This, in turn, guarantees the tty_lock() can safely be acquired (since tty->magic and tty->legacy_mutex are still a valid dereferences). The tty_lock() also gets a tty kref to prevent the tty_unlock() from dereferencing a released tty. Thus, the kref returned from get_current_tty() can be released. Lastly, the first operation of tty_reopen() is to check the tty count. If non-zero, this ensures release_tty() is not running concurrently, and the driver references have not been removed. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:50 +00:00
tty_lock(tty);
tty_kref_put(tty); /* safe to drop the kref now */
retval = tty_reopen(tty);
if (retval < 0) {
tty_unlock(tty);
tty = ERR_PTR(retval);
}
return tty;
}
/**
* tty_lookup_driver - lookup a tty driver for a given device file
* @device: device number
* @filp: file pointer to tty
* @index: index for the device in the @return driver
* @return: driver for this inode (with increased refcount)
*
* If @return is not erroneous, the caller is responsible to decrement the
* refcount by tty_driver_kref_put.
*
* Locking: tty_mutex protects get_tty_driver
*/
static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
int *index)
{
struct tty_driver *driver;
switch (device) {
#ifdef CONFIG_VT
case MKDEV(TTY_MAJOR, 0): {
extern struct tty_driver *console_driver;
driver = tty_driver_kref_get(console_driver);
*index = fg_console;
break;
}
#endif
case MKDEV(TTYAUX_MAJOR, 1): {
struct tty_driver *console_driver = console_device(index);
if (console_driver) {
driver = tty_driver_kref_get(console_driver);
if (driver) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
break;
}
}
return ERR_PTR(-ENODEV);
}
default:
driver = get_tty_driver(device, index);
if (!driver)
return ERR_PTR(-ENODEV);
break;
}
return driver;
}
/**
* tty_open_by_driver - open a tty device
* @device: dev_t of device to open
* @inode: inode of device file
* @filp: file pointer to tty
*
* Performs the driver lookup, checks for a reopen, or otherwise
* performs the first-time tty initialization.
*
* Returns the locked initialized or re-opened &tty_struct
*
* Claims the global tty_mutex to serialize:
* - concurrent first-time tty initialization
* - concurrent tty driver removal w/ lookup
* - concurrent tty removal from driver table
*/
static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
struct file *filp)
{
struct tty_struct *tty;
struct tty_driver *driver = NULL;
int index = -1;
int retval;
mutex_lock(&tty_mutex);
driver = tty_lookup_driver(device, filp, &index);
if (IS_ERR(driver)) {
mutex_unlock(&tty_mutex);
return ERR_CAST(driver);
}
/* check whether we're reopening an existing tty */
devpts: more pty driver interface cleanups This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 03:04:08 +00:00
tty = tty_driver_lookup_tty(driver, filp, index);
if (IS_ERR(tty)) {
mutex_unlock(&tty_mutex);
goto out;
}
if (tty) {
mutex_unlock(&tty_mutex);
retval = tty_lock_interruptible(tty);
tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
if (retval) {
if (retval == -EINTR)
retval = -ERESTARTSYS;
tty = ERR_PTR(retval);
goto out;
}
retval = tty_reopen(tty);
if (retval < 0) {
tty_unlock(tty);
tty = ERR_PTR(retval);
}
} else { /* Returns with the tty_lock held for now */
tty = tty_init_dev(driver, index);
mutex_unlock(&tty_mutex);
}
out:
tty_driver_kref_put(driver);
return tty;
}
/**
* tty_open - open a tty device
* @inode: inode of device file
* @filp: file pointer to tty
*
* tty_open and tty_release keep up the tty count that contains the
* number of opens done on a tty. We cannot use the inode-count, as
* different inodes might point to the same tty.
*
* Open-counting is needed for pty masters, as well as for keeping
* track of serial lines: DTR is dropped when the last close happens.
* (This is not done solely through tty->count, now. - Ted 1/27/92)
*
* The termios state of a pty is reset on first open so that
* settings don't persist across reuse.
*
* Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* tty->count should protect the rest.
* ->siglock protects ->signal/->sighand
*
* Note: the tty_unlock/lock cases without a ref are only safe due to
* tty_mutex
*/
static int tty_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty;
int noctty, retval;
dev_t device = inode->i_rdev;
unsigned saved_flags = filp->f_flags;
nonseekable_open(inode, filp);
retry_open:
retval = tty_alloc_file(filp);
if (retval)
return -ENOMEM;
tty = tty_open_current_tty(device, filp);
if (!tty)
tty = tty_open_by_driver(device, inode, filp);
tty: Re-open /dev/tty without tty_mutex Opening /dev/tty (ie., the controlling tty for the current task) is always a re-open of the underlying tty. Because holding the tty_lock is sufficient for safely re-opening a tty, and because having a tty kref is sufficient for safely acquiring the tty_lock [1], tty_open_current_tty() does not require holding tty_mutex. Repurpose tty_open_current_tty() to perform the re-open itself and refactor tty_open(). [1] Analysis of safely re-opening the current tty w/o tty_mutex get_current_tty() gets a tty kref from the already kref'ed tty value of current->signal->tty while holding the sighand lock for the current task. This guarantees that the tty pointer returned from get_current_tty() points to a tty which remains referenceable while holding the kref. Although release_tty() may run concurrently, and thus the driver reference may be removed, release_one_tty() cannot have run, and won't while holding the tty kref. This, in turn, guarantees the tty_lock() can safely be acquired (since tty->magic and tty->legacy_mutex are still a valid dereferences). The tty_lock() also gets a tty kref to prevent the tty_unlock() from dereferencing a released tty. Thus, the kref returned from get_current_tty() can be released. Lastly, the first operation of tty_reopen() is to check the tty count. If non-zero, this ensures release_tty() is not running concurrently, and the driver references have not been removed. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 17:12:50 +00:00
if (IS_ERR(tty)) {
tty_free_file(filp);
retval = PTR_ERR(tty);
if (retval != -EAGAIN || signal_pending(current))
return retval;
schedule();
goto retry_open;
}
tty_add_file(tty, filp);
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
check_tty_count(tty, __func__);
tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
if (tty->ops->open)
retval = tty->ops->open(tty, filp);
else
retval = -ENODEV;
filp->f_flags = saved_flags;
if (retval) {
tty_debug_hangup(tty, "open error %d, releasing\n", retval);
tty_unlock(tty); /* need to call tty_release without BTM */
tty_release(inode, filp);
if (retval != -ERESTARTSYS)
return retval;
if (signal_pending(current))
return retval;
schedule();
/*
* Need to reset f_op in case a hangup happened.
*/
if (tty_hung_up_p(filp))
filp->f_op = &tty_fops;
goto retry_open;
}
clear_bit(TTY_HUPPED, &tty->flags);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
read_lock(&tasklist_lock);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
spin_lock_irq(&current->sighand->siglock);
noctty = (filp->f_flags & O_NOCTTY) ||
(IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
device == MKDEV(TTYAUX_MAJOR, 1) ||
(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
if (!noctty &&
current->signal->leader &&
!current->signal->tty &&
tty->session == NULL) {
/*
* Don't let a process that only has write access to the tty
* obtain the privileges associated with having a tty as
* controlling terminal (being able to reopen it with full
* access through /dev/tty, being able to perform pushback).
* Many distributions set the group of all ttys to "tty" and
* grant write-only access to all terminals for setgid tty
* binaries, which should not imply full privileges on all ttys.
*
* This could theoretically break old code that performs open()
* on a write-only file descriptor. In that case, it might be
* necessary to also permit this if
* inode_permission(inode, MAY_READ) == 0.
*/
if (filp->f_mode & FMODE_READ)
__proc_set_tty(tty);
}
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
spin_unlock_irq(&current->sighand->siglock);
read_unlock(&tasklist_lock);
tty_unlock(tty);
return 0;
}
/**
* tty_poll - check tty status
* @filp: file being polled
* @wait: poll wait structures to update
*
* Call the line discipline polling method to obtain the poll
* status of the device.
*
* Locking: locks called line discipline but ldisc poll method
* may be re-entered freely by other callers.
*/
static unsigned int tty_poll(struct file *filp, poll_table *wait)
{
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_struct *tty = file_tty(filp);
struct tty_ldisc *ld;
int ret = 0;
if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
return 0;
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_poll(filp, wait);
if (ld->ops->poll)
ret = ld->ops->poll(tty, filp, wait);
tty_ldisc_deref(ld);
return ret;
}
static int __tty_fasync(int fd, struct file *filp, int on)
{
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_struct *tty = file_tty(filp);
unsigned long flags;
int retval = 0;
if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
goto out;
retval = fasync_helper(fd, filp, on, &tty->fasync);
if (retval <= 0)
goto out;
if (on) {
enum pid_type type;
struct pid *pid;
spin_lock_irqsave(&tty->ctrl_lock, flags);
if (tty->pgrp) {
pid = tty->pgrp;
type = PIDTYPE_PGID;
} else {
pid = task_pid(current);
type = PIDTYPE_PID;
}
Fix race in tty_fasync() properly This reverts commit 703625118069 ("tty: fix race in tty_fasync") and commit b04da8bfdfbb ("fnctl: f_modown should call write_lock_irqsave/ restore") that tried to fix up some of the fallout but was incomplete. It turns out that we really cannot hold 'tty->ctrl_lock' over calling __f_setown, because not only did that cause problems with interrupt disables (which the second commit fixed), it also causes a potential ABBA deadlock due to lock ordering. Thanks to Tetsuo Handa for following up on the issue, and running lockdep to show the problem. It goes roughly like this: - f_getown gets filp->f_owner.lock for reading without interrupts disabled, so an interrupt that happens while that lock is held can cause a lockdep chain from f_owner.lock -> sighand->siglock. - at the same time, the tty->ctrl_lock -> f_owner.lock chain that commit 703625118069 introduced, together with the pre-existing sighand->siglock -> tty->ctrl_lock chain means that we have a lock dependency the other way too. So instead of extending tty->ctrl_lock over the whole __f_setown() call, we now just take a reference to the 'pid' structure while holding the lock, and then release it after having done the __f_setown. That still guarantees that 'struct pid' won't go away from under us, which is all we really ever needed. Reported-and-tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Acked-by: Américo Wang <xiyou.wangcong@gmail.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-02-07 18:11:23 +00:00
get_pid(pid);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
__f_setown(filp, pid, type, 0);
Fix race in tty_fasync() properly This reverts commit 703625118069 ("tty: fix race in tty_fasync") and commit b04da8bfdfbb ("fnctl: f_modown should call write_lock_irqsave/ restore") that tried to fix up some of the fallout but was incomplete. It turns out that we really cannot hold 'tty->ctrl_lock' over calling __f_setown, because not only did that cause problems with interrupt disables (which the second commit fixed), it also causes a potential ABBA deadlock due to lock ordering. Thanks to Tetsuo Handa for following up on the issue, and running lockdep to show the problem. It goes roughly like this: - f_getown gets filp->f_owner.lock for reading without interrupts disabled, so an interrupt that happens while that lock is held can cause a lockdep chain from f_owner.lock -> sighand->siglock. - at the same time, the tty->ctrl_lock -> f_owner.lock chain that commit 703625118069 introduced, together with the pre-existing sighand->siglock -> tty->ctrl_lock chain means that we have a lock dependency the other way too. So instead of extending tty->ctrl_lock over the whole __f_setown() call, we now just take a reference to the 'pid' structure while holding the lock, and then release it after having done the __f_setown. That still guarantees that 'struct pid' won't go away from under us, which is all we really ever needed. Reported-and-tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Acked-by: Américo Wang <xiyou.wangcong@gmail.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-02-07 18:11:23 +00:00
put_pid(pid);
retval = 0;
}
out:
return retval;
}
static int tty_fasync(int fd, struct file *filp, int on)
{
struct tty_struct *tty = file_tty(filp);
int retval = -ENOTTY;
tty_lock(tty);
if (!tty_hung_up_p(filp))
retval = __tty_fasync(fd, filp, on);
tty_unlock(tty);
return retval;
}
/**
* tiocsti - fake input character
* @tty: tty to fake input into
* @p: pointer to character
*
* Fake input to a tty device. Does the necessary locking and
* input management.
*
* FIXME: does not honour flow control ??
*
* Locking:
* Called functions take tty_ldiscs_lock
* current->signal->tty check is safe without locks
*
* FIXME: may race normal receive processing
*/
static int tiocsti(struct tty_struct *tty, char __user *p)
{
char ch, mbz = 0;
struct tty_ldisc *ld;
if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
return -EPERM;
if (get_user(ch, p))
return -EFAULT;
tty_audit_tiocsti(tty, ch);
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return -EIO;
ld->ops->receive_buf(tty, &ch, &mbz, 1);
tty_ldisc_deref(ld);
return 0;
}
/**
* tiocgwinsz - implement window query ioctl
* @tty; tty
* @arg: user buffer for result
*
* Copies the kernel idea of the window size into the user buffer.
*
tty: Fix lock order in tty_do_resize() Commits 6a1c0680cf3ba94356ecd58833e1540c93472a57 and 9356b535fcb71db494fc434acceb79f56d15bda2, respectively 'tty: Convert termios_mutex to termios_rwsem' and 'n_tty: Access termios values safely' introduced a circular lock dependency with console_lock and termios_rwsem. The lockdep report [1] shows that n_tty_write() will attempt to claim console_lock while holding the termios_rwsem, whereas tty_do_resize() may already hold the console_lock while claiming the termios_rwsem. Since n_tty_write() and tty_do_resize() do not contend over the same data -- the tty->winsize structure -- correct the lock dependency by introducing a new lock which specifically serializes access to tty->winsize only. [1] Lockdep report ====================================================== [ INFO: possible circular locking dependency detected ] 3.10.0-0+tip-xeon+lockdep #0+tip Not tainted ------------------------------------------------------- modprobe/277 is trying to acquire lock: (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0 but task is already holding lock: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((fb_notifier_list).rwsem){.+.+.+}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b797>] down_read+0x47/0x5c [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #1 (console_lock){+.+.+.}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff810430a7>] console_lock+0x77/0x80 [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50 [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0 [<ffffffff814541b9>] tty_write+0x159/0x2e0 [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0 [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0 [<ffffffff811abec5>] SyS_write+0x55/0xa0 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #0 (&tty->termios_rwsem){++++..}: [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b other info that might help us debug this: Chain exists of: &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((fb_notifier_list).rwsem); lock(console_lock); lock((fb_notifier_list).rwsem); lock(&tty->termios_rwsem); *** DEADLOCK *** 7 locks held by modprobe/277: #0: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0 #1: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0 #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm] #3: (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320 #4: (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60 #5: (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320 #6: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 stack backtrace: CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11 04/30/2012 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007 Call Trace: [<ffffffff81755f19>] dump_stack+0x19/0x1b [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 20:43:51 +00:00
* Locking: tty->winsize_mutex is taken to ensure the winsize data
* is consistent.
*/
static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
{
int err;
tty: Fix lock order in tty_do_resize() Commits 6a1c0680cf3ba94356ecd58833e1540c93472a57 and 9356b535fcb71db494fc434acceb79f56d15bda2, respectively 'tty: Convert termios_mutex to termios_rwsem' and 'n_tty: Access termios values safely' introduced a circular lock dependency with console_lock and termios_rwsem. The lockdep report [1] shows that n_tty_write() will attempt to claim console_lock while holding the termios_rwsem, whereas tty_do_resize() may already hold the console_lock while claiming the termios_rwsem. Since n_tty_write() and tty_do_resize() do not contend over the same data -- the tty->winsize structure -- correct the lock dependency by introducing a new lock which specifically serializes access to tty->winsize only. [1] Lockdep report ====================================================== [ INFO: possible circular locking dependency detected ] 3.10.0-0+tip-xeon+lockdep #0+tip Not tainted ------------------------------------------------------- modprobe/277 is trying to acquire lock: (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0 but task is already holding lock: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((fb_notifier_list).rwsem){.+.+.+}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b797>] down_read+0x47/0x5c [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #1 (console_lock){+.+.+.}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff810430a7>] console_lock+0x77/0x80 [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50 [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0 [<ffffffff814541b9>] tty_write+0x159/0x2e0 [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0 [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0 [<ffffffff811abec5>] SyS_write+0x55/0xa0 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #0 (&tty->termios_rwsem){++++..}: [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b other info that might help us debug this: Chain exists of: &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((fb_notifier_list).rwsem); lock(console_lock); lock((fb_notifier_list).rwsem); lock(&tty->termios_rwsem); *** DEADLOCK *** 7 locks held by modprobe/277: #0: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0 #1: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0 #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm] #3: (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320 #4: (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60 #5: (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320 #6: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 stack backtrace: CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11 04/30/2012 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007 Call Trace: [<ffffffff81755f19>] dump_stack+0x19/0x1b [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 20:43:51 +00:00
mutex_lock(&tty->winsize_mutex);
err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
tty: Fix lock order in tty_do_resize() Commits 6a1c0680cf3ba94356ecd58833e1540c93472a57 and 9356b535fcb71db494fc434acceb79f56d15bda2, respectively 'tty: Convert termios_mutex to termios_rwsem' and 'n_tty: Access termios values safely' introduced a circular lock dependency with console_lock and termios_rwsem. The lockdep report [1] shows that n_tty_write() will attempt to claim console_lock while holding the termios_rwsem, whereas tty_do_resize() may already hold the console_lock while claiming the termios_rwsem. Since n_tty_write() and tty_do_resize() do not contend over the same data -- the tty->winsize structure -- correct the lock dependency by introducing a new lock which specifically serializes access to tty->winsize only. [1] Lockdep report ====================================================== [ INFO: possible circular locking dependency detected ] 3.10.0-0+tip-xeon+lockdep #0+tip Not tainted ------------------------------------------------------- modprobe/277 is trying to acquire lock: (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0 but task is already holding lock: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((fb_notifier_list).rwsem){.+.+.+}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b797>] down_read+0x47/0x5c [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #1 (console_lock){+.+.+.}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff810430a7>] console_lock+0x77/0x80 [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50 [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0 [<ffffffff814541b9>] tty_write+0x159/0x2e0 [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0 [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0 [<ffffffff811abec5>] SyS_write+0x55/0xa0 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #0 (&tty->termios_rwsem){++++..}: [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b other info that might help us debug this: Chain exists of: &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((fb_notifier_list).rwsem); lock(console_lock); lock((fb_notifier_list).rwsem); lock(&tty->termios_rwsem); *** DEADLOCK *** 7 locks held by modprobe/277: #0: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0 #1: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0 #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm] #3: (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320 #4: (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60 #5: (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320 #6: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 stack backtrace: CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11 04/30/2012 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007 Call Trace: [<ffffffff81755f19>] dump_stack+0x19/0x1b [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 20:43:51 +00:00
mutex_unlock(&tty->winsize_mutex);
return err ? -EFAULT: 0;
}
/**
* tty_do_resize - resize event
* @tty: tty being resized
* @rows: rows (character)
* @cols: cols (character)
*
* Update the termios variables and send the necessary signals to
* peform a terminal resize correctly
*/
int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
{
struct pid *pgrp;
/* Lock the tty */
tty: Fix lock order in tty_do_resize() Commits 6a1c0680cf3ba94356ecd58833e1540c93472a57 and 9356b535fcb71db494fc434acceb79f56d15bda2, respectively 'tty: Convert termios_mutex to termios_rwsem' and 'n_tty: Access termios values safely' introduced a circular lock dependency with console_lock and termios_rwsem. The lockdep report [1] shows that n_tty_write() will attempt to claim console_lock while holding the termios_rwsem, whereas tty_do_resize() may already hold the console_lock while claiming the termios_rwsem. Since n_tty_write() and tty_do_resize() do not contend over the same data -- the tty->winsize structure -- correct the lock dependency by introducing a new lock which specifically serializes access to tty->winsize only. [1] Lockdep report ====================================================== [ INFO: possible circular locking dependency detected ] 3.10.0-0+tip-xeon+lockdep #0+tip Not tainted ------------------------------------------------------- modprobe/277 is trying to acquire lock: (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0 but task is already holding lock: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((fb_notifier_list).rwsem){.+.+.+}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b797>] down_read+0x47/0x5c [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #1 (console_lock){+.+.+.}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff810430a7>] console_lock+0x77/0x80 [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50 [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0 [<ffffffff814541b9>] tty_write+0x159/0x2e0 [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0 [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0 [<ffffffff811abec5>] SyS_write+0x55/0xa0 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #0 (&tty->termios_rwsem){++++..}: [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b other info that might help us debug this: Chain exists of: &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((fb_notifier_list).rwsem); lock(console_lock); lock((fb_notifier_list).rwsem); lock(&tty->termios_rwsem); *** DEADLOCK *** 7 locks held by modprobe/277: #0: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0 #1: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0 #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm] #3: (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320 #4: (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60 #5: (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320 #6: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 stack backtrace: CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11 04/30/2012 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007 Call Trace: [<ffffffff81755f19>] dump_stack+0x19/0x1b [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 20:43:51 +00:00
mutex_lock(&tty->winsize_mutex);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
/* Signal the foreground process group */
pgrp = tty_get_pgrp(tty);
if (pgrp)
kill_pgrp(pgrp, SIGWINCH, 1);
put_pid(pgrp);
tty->winsize = *ws;
done:
tty: Fix lock order in tty_do_resize() Commits 6a1c0680cf3ba94356ecd58833e1540c93472a57 and 9356b535fcb71db494fc434acceb79f56d15bda2, respectively 'tty: Convert termios_mutex to termios_rwsem' and 'n_tty: Access termios values safely' introduced a circular lock dependency with console_lock and termios_rwsem. The lockdep report [1] shows that n_tty_write() will attempt to claim console_lock while holding the termios_rwsem, whereas tty_do_resize() may already hold the console_lock while claiming the termios_rwsem. Since n_tty_write() and tty_do_resize() do not contend over the same data -- the tty->winsize structure -- correct the lock dependency by introducing a new lock which specifically serializes access to tty->winsize only. [1] Lockdep report ====================================================== [ INFO: possible circular locking dependency detected ] 3.10.0-0+tip-xeon+lockdep #0+tip Not tainted ------------------------------------------------------- modprobe/277 is trying to acquire lock: (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0 but task is already holding lock: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((fb_notifier_list).rwsem){.+.+.+}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b797>] down_read+0x47/0x5c [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #1 (console_lock){+.+.+.}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff810430a7>] console_lock+0x77/0x80 [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50 [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0 [<ffffffff814541b9>] tty_write+0x159/0x2e0 [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0 [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0 [<ffffffff811abec5>] SyS_write+0x55/0xa0 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #0 (&tty->termios_rwsem){++++..}: [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b other info that might help us debug this: Chain exists of: &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((fb_notifier_list).rwsem); lock(console_lock); lock((fb_notifier_list).rwsem); lock(&tty->termios_rwsem); *** DEADLOCK *** 7 locks held by modprobe/277: #0: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0 #1: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0 #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm] #3: (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320 #4: (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60 #5: (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320 #6: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 stack backtrace: CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11 04/30/2012 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007 Call Trace: [<ffffffff81755f19>] dump_stack+0x19/0x1b [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 20:43:51 +00:00
mutex_unlock(&tty->winsize_mutex);
return 0;
}
EXPORT_SYMBOL(tty_do_resize);
/**
* tiocswinsz - implement window size set ioctl
* @tty; tty side of tty
* @arg: user buffer for result
*
* Copies the user idea of the window size to the kernel. Traditionally
* this is just advisory information but for the Linux console it
* actually has driver level meaning and triggers a VC resize.
*
* Locking:
* Driver dependent. The default do_resize method takes the
* tty termios mutex and ctrl_lock. The console takes its own lock
* then calls into the default method.
*/
static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
{
struct winsize tmp_ws;
if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
return -EFAULT;
if (tty->ops->resize)
return tty->ops->resize(tty, &tmp_ws);
else
return tty_do_resize(tty, &tmp_ws);
}
/**
* tioccons - allow admin to move logical console
* @file: the file to become console
*
* Allow the administrator to move the redirected console device
*
* Locking: uses redirect_lock to guard the redirect information
*/
static int tioccons(struct file *file)
{
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (file->f_op->write == redirected_tty_write) {
struct file *f;
spin_lock(&redirect_lock);
f = redirect;
redirect = NULL;
spin_unlock(&redirect_lock);
if (f)
fput(f);
return 0;
}
spin_lock(&redirect_lock);
if (redirect) {
spin_unlock(&redirect_lock);
return -EBUSY;
}
redirect = get_file(file);
spin_unlock(&redirect_lock);
return 0;
}
/**
* fionbio - non blocking ioctl
* @file: file to set blocking value
* @p: user parameter
*
* Historical tty interfaces had a blocking control ioctl before
* the generic functionality existed. This piece of history is preserved
* in the expected tty API of posix OS's.
*
* Locking: none, the open file handle ensures it won't go away.
*/
static int fionbio(struct file *file, int __user *p)
{
int nonblock;
if (get_user(nonblock, p))
return -EFAULT;
spin_lock(&file->f_lock);
if (nonblock)
file->f_flags |= O_NONBLOCK;
else
file->f_flags &= ~O_NONBLOCK;
spin_unlock(&file->f_lock);
return 0;
}
/**
* tiocsctty - set controlling tty
* @tty: tty structure
* @arg: user argument
*
* This ioctl is used to manage job control. It permits a session
* leader to set this tty as the controlling tty for the session.
*
* Locking:
* Takes tty_lock() to serialize proc_set_tty() for this tty
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* Takes tasklist_lock internally to walk sessions
* Takes ->siglock() when updating signal->tty
*/
static int tiocsctty(struct tty_struct *tty, struct file *file, int arg)
{
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
int ret = 0;
tty_lock(tty);
read_lock(&tasklist_lock);
if (current->signal->leader && (task_session(current) == tty->session))
goto unlock;
/*
* The process must be a session leader and
* not have a controlling tty already.
*/
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
if (!current->signal->leader || current->signal->tty) {
ret = -EPERM;
goto unlock;
}
if (tty->session) {
/*
* This tty is already the controlling
* tty for another session group!
*/
if (arg == 1 && capable(CAP_SYS_ADMIN)) {
/*
* Steal it away
*/
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
session_clear_tty(tty->session);
} else {
ret = -EPERM;
goto unlock;
}
}
/* See the comment in tty_open(). */
if ((file->f_mode & FMODE_READ) == 0 && !capable(CAP_SYS_ADMIN)) {
ret = -EPERM;
goto unlock;
}
proc_set_tty(tty);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
unlock:
read_unlock(&tasklist_lock);
tty_unlock(tty);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
return ret;
}
/**
* tty_get_pgrp - return a ref counted pgrp pid
* @tty: tty to read
*
* Returns a refcounted instance of the pid struct for the process
* group controlling the tty.
*/
struct pid *tty_get_pgrp(struct tty_struct *tty)
{
unsigned long flags;
struct pid *pgrp;
spin_lock_irqsave(&tty->ctrl_lock, flags);
pgrp = get_pid(tty->pgrp);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
return pgrp;
}
EXPORT_SYMBOL_GPL(tty_get_pgrp);
/*
* This checks not only the pgrp, but falls back on the pid if no
* satisfactory pgrp is found. I dunno - gdb doesn't work correctly
* without this...
*
* The caller must hold rcu lock or the tasklist lock.
*/
static struct pid *session_of_pgrp(struct pid *pgrp)
{
struct task_struct *p;
struct pid *sid = NULL;
p = pid_task(pgrp, PIDTYPE_PGID);
if (p == NULL)
p = pid_task(pgrp, PIDTYPE_PID);
if (p != NULL)
sid = task_session(p);
return sid;
}
/**
* tiocgpgrp - get process group
* @tty: tty passed by user
* @real_tty: tty side of the tty passed by the user if a pty else the tty
* @p: returned pid
*
* Obtain the process group of the tty. If there is no process group
* return an error.
*
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* Locking: none. Reference to current->signal->tty is safe.
*/
static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
struct pid *pid;
int ret;
/*
* (tty == real_tty) is a cheap way of
* testing if the tty is NOT a master pty.
*/
if (tty == real_tty && current->signal->tty != real_tty)
return -ENOTTY;
pid = tty_get_pgrp(real_tty);
ret = put_user(pid_vnr(pid), p);
put_pid(pid);
return ret;
}
/**
* tiocspgrp - attempt to set process group
* @tty: tty passed by user
* @real_tty: tty side device matching tty passed by user
* @p: pid pointer
*
* Set the process group of the tty to the session passed. Only
* permitted where the tty session is our session.
*
* Locking: RCU, ctrl lock
*/
static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
struct pid *pgrp;
pid_t pgrp_nr;
int retval = tty_check_change(real_tty);
if (retval == -EIO)
return -ENOTTY;
if (retval)
return retval;
if (!current->signal->tty ||
(current->signal->tty != real_tty) ||
(real_tty->session != task_session(current)))
return -ENOTTY;
if (get_user(pgrp_nr, p))
return -EFAULT;
if (pgrp_nr < 0)
return -EINVAL;
rcu_read_lock();
pgrp = find_vpid(pgrp_nr);
retval = -ESRCH;
if (!pgrp)
goto out_unlock;
retval = -EPERM;
if (session_of_pgrp(pgrp) != task_session(current))
goto out_unlock;
retval = 0;
spin_lock_irq(&tty->ctrl_lock);
put_pid(real_tty->pgrp);
real_tty->pgrp = get_pid(pgrp);
spin_unlock_irq(&tty->ctrl_lock);
out_unlock:
rcu_read_unlock();
return retval;
}
/**
* tiocgsid - get session id
* @tty: tty passed by user
* @real_tty: tty side of the tty passed by the user if a pty else the tty
* @p: pointer to returned session id
*
* Obtain the session id of the tty. If there is no session
* return an error.
*
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
* Locking: none. Reference to current->signal->tty is safe.
*/
static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
/*
* (tty == real_tty) is a cheap way of
* testing if the tty is NOT a master pty.
*/
if (tty == real_tty && current->signal->tty != real_tty)
return -ENOTTY;
if (!real_tty->session)
return -ENOTTY;
return put_user(pid_vnr(real_tty->session), p);
}
/**
* tiocsetd - set line discipline
* @tty: tty device
* @p: pointer to user data
*
* Set the line discipline according to user request.
*
* Locking: see tty_set_ldisc, this function is just a helper
*/
static int tiocsetd(struct tty_struct *tty, int __user *p)
{
int disc;
int ret;
if (get_user(disc, p))
return -EFAULT;
ret = tty_set_ldisc(tty, disc);
return ret;
}
/**
* tiocgetd - get line discipline
* @tty: tty device
* @p: pointer to user data
*
* Retrieves the line discipline id directly from the ldisc.
*
* Locking: waits for ldisc reference (in case the line discipline
* is changing or the tty is being hungup)
*/
static int tiocgetd(struct tty_struct *tty, int __user *p)
{
struct tty_ldisc *ld;
int ret;
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return -EIO;
ret = put_user(ld->ops->num, p);
tty_ldisc_deref(ld);
return ret;
}
/**
* send_break - performed time break
* @tty: device to break on
* @duration: timeout in mS
*
* Perform a timed break on hardware that lacks its own driver level
* timed break functionality.
*
* Locking:
* atomic_write_lock serializes
*
*/
static int send_break(struct tty_struct *tty, unsigned int duration)
{
int retval;
if (tty->ops->break_ctl == NULL)
return 0;
if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
retval = tty->ops->break_ctl(tty, duration);
else {
/* Do the work ourselves */
if (tty_write_lock(tty, 0) < 0)
return -EINTR;
retval = tty->ops->break_ctl(tty, -1);
if (retval)
goto out;
if (!signal_pending(current))
msleep_interruptible(duration);
retval = tty->ops->break_ctl(tty, 0);
out:
tty_write_unlock(tty);
if (signal_pending(current))
retval = -EINTR;
}
return retval;
}
/**
* tty_tiocmget - get modem status
* @tty: tty device
* @file: user file pointer
* @p: pointer to result
*
* Obtain the modem status bits from the tty driver if the feature
* is supported. Return -EINVAL if it is not available.
*
* Locking: none (up to the driver)
*/
static int tty_tiocmget(struct tty_struct *tty, int __user *p)
{
int retval = -EINVAL;
if (tty->ops->tiocmget) {
retval = tty->ops->tiocmget(tty);
if (retval >= 0)
retval = put_user(retval, p);
}
return retval;
}
/**
* tty_tiocmset - set modem status
* @tty: tty device
* @cmd: command - clear bits, set bits or set all
* @p: pointer to desired bits
*
* Set the modem status bits from the tty driver if the feature
* is supported. Return -EINVAL if it is not available.
*
* Locking: none (up to the driver)
*/
static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
unsigned __user *p)
{
int retval;
unsigned int set, clear, val;
if (tty->ops->tiocmset == NULL)
return -EINVAL;
retval = get_user(val, p);
if (retval)
return retval;
set = clear = 0;
switch (cmd) {
case TIOCMBIS:
set = val;
break;
case TIOCMBIC:
clear = val;
break;
case TIOCMSET:
set = val;
clear = ~val;
break;
}
set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
return tty->ops->tiocmset(tty, set, clear);
}
static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
{
int retval = -EINVAL;
struct serial_icounter_struct icount;
memset(&icount, 0, sizeof(icount));
if (tty->ops->get_icount)
retval = tty->ops->get_icount(tty, &icount);
if (retval != 0)
return retval;
if (copy_to_user(arg, &icount, sizeof(icount)))
return -EFAULT;
return 0;
}
static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
{
static DEFINE_RATELIMIT_STATE(depr_flags,
DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
char comm[TASK_COMM_LEN];
int flags;
if (get_user(flags, &ss->flags))
return;
flags &= ASYNC_DEPRECATED;
if (flags && __ratelimit(&depr_flags))
pr_warning("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
__func__, get_task_comm(comm, current), flags);
}
/*
* if pty, return the slave side (real_tty)
* otherwise, return self
*/
static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
{
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
tty = tty->link;
return tty;
}
/*
* Split this up, as gcc can choke on it otherwise..
*/
long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_struct *tty = file_tty(file);
struct tty_struct *real_tty;
void __user *p = (void __user *)arg;
int retval;
struct tty_ldisc *ld;
if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
return -EINVAL;
real_tty = tty_pair_get_tty(tty);
/*
* Factor out some common prep work
*/
switch (cmd) {
case TIOCSETD:
case TIOCSBRK:
case TIOCCBRK:
case TCSBRK:
case TCSBRKP:
retval = tty_check_change(tty);
if (retval)
return retval;
if (cmd != TIOCCBRK) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
return -EINTR;
}
break;
}
/*
* Now do the stuff.
*/
switch (cmd) {
case TIOCSTI:
return tiocsti(tty, p);
case TIOCGWINSZ:
return tiocgwinsz(real_tty, p);
case TIOCSWINSZ:
return tiocswinsz(real_tty, p);
case TIOCCONS:
return real_tty != tty ? -EINVAL : tioccons(file);
case FIONBIO:
return fionbio(file, p);
case TIOCEXCL:
set_bit(TTY_EXCLUSIVE, &tty->flags);
return 0;
case TIOCNXCL:
clear_bit(TTY_EXCLUSIVE, &tty->flags);
return 0;
case TIOCGEXCL:
{
int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
return put_user(excl, (int __user *)p);
}
case TIOCNOTTY:
if (current->signal->tty != tty)
return -ENOTTY;
no_tty();
return 0;
case TIOCSCTTY:
return tiocsctty(real_tty, file, arg);
case TIOCGPGRP:
return tiocgpgrp(tty, real_tty, p);
case TIOCSPGRP:
return tiocspgrp(tty, real_tty, p);
case TIOCGSID:
return tiocgsid(tty, real_tty, p);
case TIOCGETD:
return tiocgetd(tty, p);
case TIOCSETD:
return tiocsetd(tty, p);
case TIOCVHANGUP:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
tty_vhangup(tty);
return 0;
case TIOCGDEV:
{
unsigned int ret = new_encode_dev(tty_devnum(real_tty));
return put_user(ret, (unsigned int __user *)p);
}
/*
* Break handling
*/
case TIOCSBRK: /* Turn break on, unconditionally */
if (tty->ops->break_ctl)
return tty->ops->break_ctl(tty, -1);
return 0;
case TIOCCBRK: /* Turn break off, unconditionally */
if (tty->ops->break_ctl)
return tty->ops->break_ctl(tty, 0);
return 0;
case TCSBRK: /* SVID version: non-zero arg --> no break */
/* non-zero arg means wait for all output data
* to be sent (performed above) but don't send break.
* This is used by the tcdrain() termios function.
*/
if (!arg)
return send_break(tty, 250);
return 0;
case TCSBRKP: /* support for POSIX tcsendbreak() */
return send_break(tty, arg ? arg*100 : 250);
case TIOCMGET:
return tty_tiocmget(tty, p);
case TIOCMSET:
case TIOCMBIC:
case TIOCMBIS:
return tty_tiocmset(tty, cmd, p);
case TIOCGICOUNT:
retval = tty_tiocgicount(tty, p);
/* For the moment allow fall through to the old method */
if (retval != -EINVAL)
return retval;
break;
case TCFLSH:
switch (arg) {
case TCIFLUSH:
case TCIOFLUSH:
/* flush tty buffer and allow ldisc to process ioctl */
tty_buffer_flush(tty, NULL);
break;
}
break;
case TIOCSSERIAL:
tty_warn_deprecated_flags(p);
break;
}
if (tty->ops->ioctl) {
retval = tty->ops->ioctl(tty, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_ioctl(file, cmd, arg);
retval = -EINVAL;
if (ld->ops->ioctl) {
retval = ld->ops->ioctl(tty, file, cmd, arg);
if (retval == -ENOIOCTLCMD)
retval = -ENOTTY;
}
tty_ldisc_deref(ld);
return retval;
}
#ifdef CONFIG_COMPAT
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-17 18:37:36 +00:00
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
int retval = -ENOIOCTLCMD;
if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
return -EINVAL;
if (tty->ops->compat_ioctl) {
retval = tty->ops->compat_ioctl(tty, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_compat_ioctl(file, cmd, arg);
if (ld->ops->compat_ioctl)
retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
else
retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
tty_ldisc_deref(ld);
return retval;
}
#endif
static int this_tty(const void *t, struct file *file, unsigned fd)
{
if (likely(file->f_op->read != tty_read))
return 0;
return file_tty(file) != t ? 0 : fd + 1;
}
/*
* This implements the "Secure Attention Key" --- the idea is to
* prevent trojan horses by killing all processes associated with this
* tty when the user hits the "Secure Attention Key". Required for
* super-paranoid applications --- see the Orange Book for more details.
*
* This code could be nicer; ideally it should send a HUP, wait a few
* seconds, then send a INT, and then a KILL signal. But you then
* have to coordinate with the init process, since all processes associated
* with the current tty must be dead before the new getty is allowed
* to spawn.
*
* Now, if it would be correct ;-/ The current code has a nasty hole -
* it doesn't catch files in flight. We may send the descriptor to ourselves
* via AF_UNIX socket, close it and later fetch from socket. FIXME.
*
* Nasty bug: do_SAK is being called in interrupt context. This can
* deadlock. We punt it up to process context. AKPM - 16Mar2001
*/
void __do_SAK(struct tty_struct *tty)
{
#ifdef TTY_SOFT_SAK
tty_hangup(tty);
#else
struct task_struct *g, *p;
struct pid *session;
int i;
if (!tty)
return;
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
session = tty->session;
tty_ldisc_flush(tty);
tty_driver_flush_buffer(tty);
read_lock(&tasklist_lock);
/* Kill the entire session */
do_each_pid_task(session, PIDTYPE_SID, p) {
tty_notice(tty, "SAK: killed process %d (%s): by session\n",
task_pid_nr(p), p->comm);
send_sig(SIGKILL, p, 1);
} while_each_pid_task(session, PIDTYPE_SID, p);
/* Now kill any processes that happen to have the tty open */
do_each_thread(g, p) {
if (p->signal->tty == tty) {
tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
task_pid_nr(p), p->comm);
send_sig(SIGKILL, p, 1);
continue;
}
task_lock(p);
i = iterate_fd(p->files, 0, this_tty, tty);
if (i != 0) {
tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
task_pid_nr(p), p->comm, i - 1);
force_sig(SIGKILL, p);
}
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
#endif
}
static void do_SAK_work(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, SAK_work);
__do_SAK(tty);
}
/*
* The tq handling here is a little racy - tty->SAK_work may already be queued.
* Fortunately we don't need to worry, because if ->SAK_work is already queued,
* the values which we write to it will be identical to the values which it
* already has. --akpm
*/
void do_SAK(struct tty_struct *tty)
{
if (!tty)
return;
schedule_work(&tty->SAK_work);
}
EXPORT_SYMBOL(do_SAK);
static int dev_match_devt(struct device *dev, const void *data)
{
const dev_t *devt = data;
return dev->devt == *devt;
}
/* Must put_device() after it's unused! */
static struct device *tty_get_device(struct tty_struct *tty)
{
dev_t devt = tty_devnum(tty);
return class_find_device(tty_class, NULL, &devt, dev_match_devt);
}
/**
* alloc_tty_struct
*
* This subroutine allocates and initializes a tty structure.
*
* Locking: none - tty in question is not exposed at this point
*/
struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;
tty = kzalloc(sizeof(*tty), GFP_KERNEL);
if (!tty)
return NULL;
kref_init(&tty->kref);
tty->magic = TTY_MAGIC;
tty_ldisc_init(tty);
tty->session = NULL;
tty->pgrp = NULL;
mutex_init(&tty->legacy_mutex);
mutex_init(&tty->throttle_mutex);
init_rwsem(&tty->termios_rwsem);
tty: Fix lock order in tty_do_resize() Commits 6a1c0680cf3ba94356ecd58833e1540c93472a57 and 9356b535fcb71db494fc434acceb79f56d15bda2, respectively 'tty: Convert termios_mutex to termios_rwsem' and 'n_tty: Access termios values safely' introduced a circular lock dependency with console_lock and termios_rwsem. The lockdep report [1] shows that n_tty_write() will attempt to claim console_lock while holding the termios_rwsem, whereas tty_do_resize() may already hold the console_lock while claiming the termios_rwsem. Since n_tty_write() and tty_do_resize() do not contend over the same data -- the tty->winsize structure -- correct the lock dependency by introducing a new lock which specifically serializes access to tty->winsize only. [1] Lockdep report ====================================================== [ INFO: possible circular locking dependency detected ] 3.10.0-0+tip-xeon+lockdep #0+tip Not tainted ------------------------------------------------------- modprobe/277 is trying to acquire lock: (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0 but task is already holding lock: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((fb_notifier_list).rwsem){.+.+.+}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b797>] down_read+0x47/0x5c [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #1 (console_lock){+.+.+.}: [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff810430a7>] console_lock+0x77/0x80 [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50 [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0 [<ffffffff814541b9>] tty_write+0x159/0x2e0 [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0 [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0 [<ffffffff811abec5>] SyS_write+0x55/0xa0 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b -> #0 (&tty->termios_rwsem){++++..}: [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b other info that might help us debug this: Chain exists of: &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((fb_notifier_list).rwsem); lock(console_lock); lock((fb_notifier_list).rwsem); lock(&tty->termios_rwsem); *** DEADLOCK *** 7 locks held by modprobe/277: #0: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0 #1: (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0 #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm] #3: (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320 #4: (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60 #5: (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320 #6: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0 stack backtrace: CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11 04/30/2012 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007 Call Trace: [<ffffffff81755f19>] dump_stack+0x19/0x1b [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff8175b724>] down_write+0x44/0x70 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0 [<ffffffff81452656>] tty_do_resize+0x36/0xe0 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0 [<ffffffff8146c99f>] vc_resize+0x1f/0x30 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0 [<ffffffff8146a4bc>] visual_init+0xbc/0x120 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper] [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper] [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau] [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau] [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm] [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau] [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80 [<ffffffff813b1701>] pci_device_probe+0x111/0x120 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0 [<ffffffff81497bab>] __driver_attach+0xab/0xb0 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0 [<ffffffff814971fe>] driver_attach+0x1e/0x20 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff814982b7>] driver_register+0x77/0x170 [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffff813b0454>] __pci_register_driver+0x64/0x70 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm] [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a000>] ? 0xffffffffa0229fff [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau] [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 20:43:51 +00:00
mutex_init(&tty->winsize_mutex);
init_ldsem(&tty->ldisc_sem);
init_waitqueue_head(&tty->write_wait);
init_waitqueue_head(&tty->read_wait);
2006-11-22 14:55:48 +00:00
INIT_WORK(&tty->hangup_work, do_tty_hangup);
mutex_init(&tty->atomic_write_lock);
spin_lock_init(&tty->ctrl_lock);
spin_lock_init(&tty->flow_lock);
spin_lock_init(&tty->files_lock);
INIT_LIST_HEAD(&tty->tty_files);
INIT_WORK(&tty->SAK_work, do_SAK_work);
tty->driver = driver;
tty->ops = driver->ops;
tty->index = idx;
tty_line_name(driver, idx, tty->name);
tty->dev = tty_get_device(tty);
return tty;
}
/**
* tty_put_char - write one character to a tty
* @tty: tty
* @ch: character
*
* Write one byte to the tty using the provided put_char method
* if present. Returns the number of characters successfully output.
*
* Note: the specific put_char operation in the driver layer may go
* away soon. Don't call it directly, use this method
*/
int tty_put_char(struct tty_struct *tty, unsigned char ch)
{
if (tty->ops->put_char)
return tty->ops->put_char(tty, ch);
return tty->ops->write(tty, &ch, 1);
}
EXPORT_SYMBOL_GPL(tty_put_char);
struct class *tty_class;
static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
unsigned int index, unsigned int count)
{
int err;
/* init here, since reused cdevs cause crashes */
driver->cdevs[index] = cdev_alloc();
if (!driver->cdevs[index])
return -ENOMEM;
driver->cdevs[index]->ops = &tty_fops;
driver->cdevs[index]->owner = driver->owner;
err = cdev_add(driver->cdevs[index], dev, count);
if (err)
kobject_put(&driver->cdevs[index]->kobj);
return err;
}
/**
* tty_register_device - register a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
* @device: a struct device that is associated with this tty device.
* This field is optional, if there is no known struct device
* for this tty device it can be set to NULL safely.
*
* Returns a pointer to the struct device for this tty device
* (or ERR_PTR(-EFOO) on error).
*
* This call is required to be made to register an individual tty device
* if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
* that bit is not set, this function should not be called by a tty
* driver.
*
* Locking: ??
*/
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
struct device *device)
{
return tty_register_device_attr(driver, index, device, NULL, NULL);
}
EXPORT_SYMBOL(tty_register_device);
static void tty_device_create_release(struct device *dev)
{
dev_dbg(dev, "releasing...\n");
kfree(dev);
}
/**
* tty_register_device_attr - register a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
* @device: a struct device that is associated with this tty device.
* This field is optional, if there is no known struct device
* for this tty device it can be set to NULL safely.
* @drvdata: Driver data to be set to device.
* @attr_grp: Attribute group to be set on device.
*
* Returns a pointer to the struct device for this tty device
* (or ERR_PTR(-EFOO) on error).
*
* This call is required to be made to register an individual tty device
* if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
* that bit is not set, this function should not be called by a tty
* driver.
*
* Locking: ??
*/
struct device *tty_register_device_attr(struct tty_driver *driver,
unsigned index, struct device *device,
void *drvdata,
const struct attribute_group **attr_grp)
{
char name[64];
dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
struct device *dev = NULL;
int retval = -ENODEV;
bool cdev = false;
if (index >= driver->num) {
pr_err("%s: Attempt to register invalid tty line number (%d)\n",
driver->name, index);
return ERR_PTR(-EINVAL);
}
if (driver->type == TTY_DRIVER_TYPE_PTY)
pty_line_name(driver, index, name);
else
tty_line_name(driver, index, name);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
retval = tty_cdev_add(driver, devt, index, 1);
if (retval)
goto error;
cdev = true;
}
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev) {
retval = -ENOMEM;
goto error;
}
dev->devt = devt;
dev->class = tty_class;
dev->parent = device;
dev->release = tty_device_create_release;
dev_set_name(dev, "%s", name);
dev->groups = attr_grp;
dev_set_drvdata(dev, drvdata);
retval = device_register(dev);
if (retval)
goto error;
return dev;
error:
put_device(dev);
if (cdev) {
cdev_del(driver->cdevs[index]);
driver->cdevs[index] = NULL;
}
return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(tty_register_device_attr);
/**
* tty_unregister_device - unregister a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
*
* If a tty device is registered with a call to tty_register_device() then
* this function must be called when the tty device is gone.
*
* Locking: ??
*/
void tty_unregister_device(struct tty_driver *driver, unsigned index)
{
device_destroy(tty_class,
MKDEV(driver->major, driver->minor_start) + index);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
cdev_del(driver->cdevs[index]);
driver->cdevs[index] = NULL;
}
}
EXPORT_SYMBOL(tty_unregister_device);
/**
* __tty_alloc_driver -- allocate tty driver
* @lines: count of lines this driver can handle at most
* @owner: module which is repsonsible for this driver
* @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
*
* This should not be called directly, some of the provided macros should be
* used instead. Use IS_ERR and friends on @retval.
*/
struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
unsigned long flags)
{
struct tty_driver *driver;
unsigned int cdevs = 1;
int err;
if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
return ERR_PTR(-EINVAL);
driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
if (!driver)
return ERR_PTR(-ENOMEM);
kref_init(&driver->kref);
driver->magic = TTY_DRIVER_MAGIC;
driver->num = lines;
driver->owner = owner;
driver->flags = flags;
if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
GFP_KERNEL);
driver->termios = kcalloc(lines, sizeof(*driver->termios),
GFP_KERNEL);
if (!driver->ttys || !driver->termios) {
err = -ENOMEM;
goto err_free_all;
}
}
if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
driver->ports = kcalloc(lines, sizeof(*driver->ports),
GFP_KERNEL);
if (!driver->ports) {
err = -ENOMEM;
goto err_free_all;
}
cdevs = lines;
}
driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
if (!driver->cdevs) {
err = -ENOMEM;
goto err_free_all;
}
return driver;
err_free_all:
kfree(driver->ports);
kfree(driver->ttys);
kfree(driver->termios);
kfree(driver->cdevs);
kfree(driver);
return ERR_PTR(err);
}
EXPORT_SYMBOL(__tty_alloc_driver);
static void destruct_tty_driver(struct kref *kref)
{
struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
int i;
struct ktermios *tp;
if (driver->flags & TTY_DRIVER_INSTALLED) {
/*
* Free the termios and termios_locked structures because
* we don't want to get memory leaks when modular tty
* drivers are removed from the kernel.
*/
for (i = 0; i < driver->num; i++) {
tp = driver->termios[i];
if (tp) {
driver->termios[i] = NULL;
kfree(tp);
}
if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
tty_unregister_device(driver, i);
}
proc_tty_unregister_driver(driver);
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
cdev_del(driver->cdevs[0]);
}
kfree(driver->cdevs);
kfree(driver->ports);
kfree(driver->termios);
kfree(driver->ttys);
kfree(driver);
}
void tty_driver_kref_put(struct tty_driver *driver)
{
kref_put(&driver->kref, destruct_tty_driver);
}
EXPORT_SYMBOL(tty_driver_kref_put);
void tty_set_operations(struct tty_driver *driver,
const struct tty_operations *op)
{
driver->ops = op;
};
EXPORT_SYMBOL(tty_set_operations);
void put_tty_driver(struct tty_driver *d)
{
tty_driver_kref_put(d);
}
EXPORT_SYMBOL(put_tty_driver);
/*
* Called by a tty driver to register itself.
*/
int tty_register_driver(struct tty_driver *driver)
{
int error;
int i;
dev_t dev;
struct device *d;
if (!driver->major) {
error = alloc_chrdev_region(&dev, driver->minor_start,
driver->num, driver->name);
if (!error) {
driver->major = MAJOR(dev);
driver->minor_start = MINOR(dev);
}
} else {
dev = MKDEV(driver->major, driver->minor_start);
error = register_chrdev_region(dev, driver->num, driver->name);
}
if (error < 0)
goto err;
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
error = tty_cdev_add(driver, dev, 0, driver->num);
if (error)
goto err_unreg_char;
}
Protect tty drivers list with tty_mutex Additions and removal from tty_drivers list were just done as well as iterating on it for /proc/tty/drivers generation. testing: modprobe/rmmod loop of simple module which does nothing but tty_register_driver() vs cat /proc/tty/drivers loop BUG: unable to handle kernel paging request at virtual address 6b6b6b6b printing eip: c01cefa7 *pde = 00000000 Oops: 0000 [#1] PREEMPT last sysfs file: devices/pci0000:00/0000:00:1d.7/usb5/5-0:1.0/bInterfaceProtocol Modules linked in: ohci_hcd af_packet e1000 ehci_hcd uhci_hcd usbcore xfs CPU: 0 EIP: 0060:[<c01cefa7>] Not tainted VLI EFLAGS: 00010297 (2.6.21-rc4-mm1 #4) EIP is at vsnprintf+0x3a4/0x5fc eax: 6b6b6b6b ebx: f6cb50f2 ecx: 6b6b6b6b edx: fffffffe esi: c0354700 edi: f6cb6000 ebp: 6b6b6b6b esp: f31f5e68 ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 Process cat (pid: 31864, ti=f31f4000 task=c1998030 task.ti=f31f4000) Stack: 00000000 c0103f20 c013003a c0103f20 00000000 f6cb50da 0000000a 00000f0e f6cb50f2 00000010 00000014 ffffffff ffffffff 00000007 c0354753 f6cb50f2 f73e39dc f73e39dc 00000001 c0175416 f31f5ed8 f31f5ed4 0ee00000 f32090bc Call Trace: [<c0103f20>] restore_nocheck+0x12/0x15 [<c013003a>] mark_held_locks+0x6d/0x86 [<c0103f20>] restore_nocheck+0x12/0x15 [<c0175416>] seq_printf+0x2e/0x52 [<c0192895>] show_tty_range+0x35/0x1f3 [<c0175416>] seq_printf+0x2e/0x52 [<c0192add>] show_tty_driver+0x8a/0x1d9 [<c01758f6>] seq_read+0x70/0x2ba [<c0175886>] seq_read+0x0/0x2ba [<c018d8e6>] proc_reg_read+0x63/0x9f [<c015e764>] vfs_read+0x7d/0xb5 [<c018d883>] proc_reg_read+0x0/0x9f [<c015eab1>] sys_read+0x41/0x6a [<c0103e4e>] sysenter_past_esp+0x5f/0x99 ======================= Code: 00 8b 4d 04 e9 44 ff ff ff 8d 4d 04 89 4c 24 50 8b 6d 00 81 fd ff 0f 00 00 b8 a4 c1 35 c0 0f 46 e8 8b 54 24 2c 89 e9 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 89 c6 8b 44 24 28 89 EIP: [<c01cefa7>] vsnprintf+0x3a4/0x5fc SS:ESP 0068:f31f5e68 Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 07:27:12 +00:00
mutex_lock(&tty_mutex);
list_add(&driver->tty_drivers, &tty_drivers);
Protect tty drivers list with tty_mutex Additions and removal from tty_drivers list were just done as well as iterating on it for /proc/tty/drivers generation. testing: modprobe/rmmod loop of simple module which does nothing but tty_register_driver() vs cat /proc/tty/drivers loop BUG: unable to handle kernel paging request at virtual address 6b6b6b6b printing eip: c01cefa7 *pde = 00000000 Oops: 0000 [#1] PREEMPT last sysfs file: devices/pci0000:00/0000:00:1d.7/usb5/5-0:1.0/bInterfaceProtocol Modules linked in: ohci_hcd af_packet e1000 ehci_hcd uhci_hcd usbcore xfs CPU: 0 EIP: 0060:[<c01cefa7>] Not tainted VLI EFLAGS: 00010297 (2.6.21-rc4-mm1 #4) EIP is at vsnprintf+0x3a4/0x5fc eax: 6b6b6b6b ebx: f6cb50f2 ecx: 6b6b6b6b edx: fffffffe esi: c0354700 edi: f6cb6000 ebp: 6b6b6b6b esp: f31f5e68 ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 Process cat (pid: 31864, ti=f31f4000 task=c1998030 task.ti=f31f4000) Stack: 00000000 c0103f20 c013003a c0103f20 00000000 f6cb50da 0000000a 00000f0e f6cb50f2 00000010 00000014 ffffffff ffffffff 00000007 c0354753 f6cb50f2 f73e39dc f73e39dc 00000001 c0175416 f31f5ed8 f31f5ed4 0ee00000 f32090bc Call Trace: [<c0103f20>] restore_nocheck+0x12/0x15 [<c013003a>] mark_held_locks+0x6d/0x86 [<c0103f20>] restore_nocheck+0x12/0x15 [<c0175416>] seq_printf+0x2e/0x52 [<c0192895>] show_tty_range+0x35/0x1f3 [<c0175416>] seq_printf+0x2e/0x52 [<c0192add>] show_tty_driver+0x8a/0x1d9 [<c01758f6>] seq_read+0x70/0x2ba [<c0175886>] seq_read+0x0/0x2ba [<c018d8e6>] proc_reg_read+0x63/0x9f [<c015e764>] vfs_read+0x7d/0xb5 [<c018d883>] proc_reg_read+0x0/0x9f [<c015eab1>] sys_read+0x41/0x6a [<c0103e4e>] sysenter_past_esp+0x5f/0x99 ======================= Code: 00 8b 4d 04 e9 44 ff ff ff 8d 4d 04 89 4c 24 50 8b 6d 00 81 fd ff 0f 00 00 b8 a4 c1 35 c0 0f 46 e8 8b 54 24 2c 89 e9 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 89 c6 8b 44 24 28 89 EIP: [<c01cefa7>] vsnprintf+0x3a4/0x5fc SS:ESP 0068:f31f5e68 Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 07:27:12 +00:00
mutex_unlock(&tty_mutex);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
for (i = 0; i < driver->num; i++) {
d = tty_register_device(driver, i, NULL);
if (IS_ERR(d)) {
error = PTR_ERR(d);
goto err_unreg_devs;
}
}
}
proc_tty_register_driver(driver);
driver->flags |= TTY_DRIVER_INSTALLED;
return 0;
err_unreg_devs:
for (i--; i >= 0; i--)
tty_unregister_device(driver, i);
mutex_lock(&tty_mutex);
list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
err_unreg_char:
unregister_chrdev_region(dev, driver->num);
err:
return error;
}
EXPORT_SYMBOL(tty_register_driver);
/*
* Called by a tty driver to unregister itself.
*/
int tty_unregister_driver(struct tty_driver *driver)
{
#if 0
/* FIXME */
if (driver->refcount)
return -EBUSY;
#endif
unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
driver->num);
Protect tty drivers list with tty_mutex Additions and removal from tty_drivers list were just done as well as iterating on it for /proc/tty/drivers generation. testing: modprobe/rmmod loop of simple module which does nothing but tty_register_driver() vs cat /proc/tty/drivers loop BUG: unable to handle kernel paging request at virtual address 6b6b6b6b printing eip: c01cefa7 *pde = 00000000 Oops: 0000 [#1] PREEMPT last sysfs file: devices/pci0000:00/0000:00:1d.7/usb5/5-0:1.0/bInterfaceProtocol Modules linked in: ohci_hcd af_packet e1000 ehci_hcd uhci_hcd usbcore xfs CPU: 0 EIP: 0060:[<c01cefa7>] Not tainted VLI EFLAGS: 00010297 (2.6.21-rc4-mm1 #4) EIP is at vsnprintf+0x3a4/0x5fc eax: 6b6b6b6b ebx: f6cb50f2 ecx: 6b6b6b6b edx: fffffffe esi: c0354700 edi: f6cb6000 ebp: 6b6b6b6b esp: f31f5e68 ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 Process cat (pid: 31864, ti=f31f4000 task=c1998030 task.ti=f31f4000) Stack: 00000000 c0103f20 c013003a c0103f20 00000000 f6cb50da 0000000a 00000f0e f6cb50f2 00000010 00000014 ffffffff ffffffff 00000007 c0354753 f6cb50f2 f73e39dc f73e39dc 00000001 c0175416 f31f5ed8 f31f5ed4 0ee00000 f32090bc Call Trace: [<c0103f20>] restore_nocheck+0x12/0x15 [<c013003a>] mark_held_locks+0x6d/0x86 [<c0103f20>] restore_nocheck+0x12/0x15 [<c0175416>] seq_printf+0x2e/0x52 [<c0192895>] show_tty_range+0x35/0x1f3 [<c0175416>] seq_printf+0x2e/0x52 [<c0192add>] show_tty_driver+0x8a/0x1d9 [<c01758f6>] seq_read+0x70/0x2ba [<c0175886>] seq_read+0x0/0x2ba [<c018d8e6>] proc_reg_read+0x63/0x9f [<c015e764>] vfs_read+0x7d/0xb5 [<c018d883>] proc_reg_read+0x0/0x9f [<c015eab1>] sys_read+0x41/0x6a [<c0103e4e>] sysenter_past_esp+0x5f/0x99 ======================= Code: 00 8b 4d 04 e9 44 ff ff ff 8d 4d 04 89 4c 24 50 8b 6d 00 81 fd ff 0f 00 00 b8 a4 c1 35 c0 0f 46 e8 8b 54 24 2c 89 e9 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 89 c6 8b 44 24 28 89 EIP: [<c01cefa7>] vsnprintf+0x3a4/0x5fc SS:ESP 0068:f31f5e68 Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 07:27:12 +00:00
mutex_lock(&tty_mutex);
list_del(&driver->tty_drivers);
Protect tty drivers list with tty_mutex Additions and removal from tty_drivers list were just done as well as iterating on it for /proc/tty/drivers generation. testing: modprobe/rmmod loop of simple module which does nothing but tty_register_driver() vs cat /proc/tty/drivers loop BUG: unable to handle kernel paging request at virtual address 6b6b6b6b printing eip: c01cefa7 *pde = 00000000 Oops: 0000 [#1] PREEMPT last sysfs file: devices/pci0000:00/0000:00:1d.7/usb5/5-0:1.0/bInterfaceProtocol Modules linked in: ohci_hcd af_packet e1000 ehci_hcd uhci_hcd usbcore xfs CPU: 0 EIP: 0060:[<c01cefa7>] Not tainted VLI EFLAGS: 00010297 (2.6.21-rc4-mm1 #4) EIP is at vsnprintf+0x3a4/0x5fc eax: 6b6b6b6b ebx: f6cb50f2 ecx: 6b6b6b6b edx: fffffffe esi: c0354700 edi: f6cb6000 ebp: 6b6b6b6b esp: f31f5e68 ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 Process cat (pid: 31864, ti=f31f4000 task=c1998030 task.ti=f31f4000) Stack: 00000000 c0103f20 c013003a c0103f20 00000000 f6cb50da 0000000a 00000f0e f6cb50f2 00000010 00000014 ffffffff ffffffff 00000007 c0354753 f6cb50f2 f73e39dc f73e39dc 00000001 c0175416 f31f5ed8 f31f5ed4 0ee00000 f32090bc Call Trace: [<c0103f20>] restore_nocheck+0x12/0x15 [<c013003a>] mark_held_locks+0x6d/0x86 [<c0103f20>] restore_nocheck+0x12/0x15 [<c0175416>] seq_printf+0x2e/0x52 [<c0192895>] show_tty_range+0x35/0x1f3 [<c0175416>] seq_printf+0x2e/0x52 [<c0192add>] show_tty_driver+0x8a/0x1d9 [<c01758f6>] seq_read+0x70/0x2ba [<c0175886>] seq_read+0x0/0x2ba [<c018d8e6>] proc_reg_read+0x63/0x9f [<c015e764>] vfs_read+0x7d/0xb5 [<c018d883>] proc_reg_read+0x0/0x9f [<c015eab1>] sys_read+0x41/0x6a [<c0103e4e>] sysenter_past_esp+0x5f/0x99 ======================= Code: 00 8b 4d 04 e9 44 ff ff ff 8d 4d 04 89 4c 24 50 8b 6d 00 81 fd ff 0f 00 00 b8 a4 c1 35 c0 0f 46 e8 8b 54 24 2c 89 e9 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 89 c6 8b 44 24 28 89 EIP: [<c01cefa7>] vsnprintf+0x3a4/0x5fc SS:ESP 0068:f31f5e68 Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 07:27:12 +00:00
mutex_unlock(&tty_mutex);
return 0;
}
EXPORT_SYMBOL(tty_unregister_driver);
[PATCH] tty: ->signal->tty locking Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 10:36:04 +00:00
dev_t tty_devnum(struct tty_struct *tty)
{
return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
}
EXPORT_SYMBOL(tty_devnum);
void tty_default_fops(struct file_operations *fops)
{
*fops = tty_fops;
}
/*
* Initialize the console device. This is called *early*, so
* we can't necessarily depend on lots of kernel help here.
* Just do some early initializations, and do the complex setup
* later.
*/
void __init console_init(void)
{
initcall_t *call;
/* Setup the default TTY line discipline. */
n_tty_init();
/*
* set up the console device so that later boot sequences can
* inform about problems etc..
*/
call = __con_initcall_start;
while (call < __con_initcall_end) {
(*call)();
call++;
}
}
static char *tty_devnode(struct device *dev, umode_t *mode)
{
if (!mode)
return NULL;
if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
dev->devt == MKDEV(TTYAUX_MAJOR, 2))
*mode = 0666;
return NULL;
}
static int __init tty_class_init(void)
{
tty_class = class_create(THIS_MODULE, "tty");
if (IS_ERR(tty_class))
return PTR_ERR(tty_class);
tty_class->devnode = tty_devnode;
return 0;
}
postcore_initcall(tty_class_init);
/* 3/2004 jmc: why do these devices exist? */
static struct cdev tty_cdev, console_cdev;
static ssize_t show_cons_active(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct console *cs[16];
int i = 0;
struct console *c;
ssize_t count = 0;
console_lock();
for_each_console(c) {
if (!c->device)
continue;
if (!c->write)
continue;
if ((c->flags & CON_ENABLED) == 0)
continue;
cs[i++] = c;
if (i >= ARRAY_SIZE(cs))
break;
}
while (i--) {
int index = cs[i]->index;
struct tty_driver *drv = cs[i]->device(cs[i], &index);
/* don't resolve tty0 as some programs depend on it */
if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
count += tty_line_name(drv, index, buf + count);
else
count += sprintf(buf + count, "%s%d",
cs[i]->name, cs[i]->index);
count += sprintf(buf + count, "%c", i ? ' ':'\n');
}
console_unlock();
return count;
}
static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
static struct attribute *cons_dev_attrs[] = {
&dev_attr_active.attr,
NULL
};
ATTRIBUTE_GROUPS(cons_dev);
static struct device *consdev;
void console_sysfs_notify(void)
{
if (consdev)
sysfs_notify(&consdev->kobj, NULL, "active");
}
/*
* Ok, now we can initialize the rest of the tty devices and can count
* on memory allocations, interrupts etc..
*/
int __init tty_init(void)
{
cdev_init(&tty_cdev, &tty_fops);
if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
panic("Couldn't register /dev/tty driver\n");
device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
cdev_init(&console_cdev, &console_fops);
if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
panic("Couldn't register /dev/console driver\n");
consdev = device_create_with_groups(tty_class, NULL,
MKDEV(TTYAUX_MAJOR, 1), NULL,
cons_dev_groups, "console");
if (IS_ERR(consdev))
consdev = NULL;
#ifdef CONFIG_VT
vty_init(&console_fops);
#endif
return 0;
}