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tty: Drop krefs for interrupted tty lock

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When the tty lock is interrupted on attempted re-open, 2 tty krefs
are still held. Drop extra kref before returning failure from
tty_lock_interruptible(), and drop lookup kref before returning
failure from tty_open().

Fixes: 0bfd464d3f ("tty: Wait interruptibly for tty lock on reopen")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2016-02-05 10:49:36 -08:00 committed by Greg Kroah-Hartman
parent 36f90b0a2d
commit e9036d0662
2 changed files with 7 additions and 3 deletions
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3
drivers/tty/tty_io.c
View file

@ -2066,13 +2066,12 @@ static int tty_open(struct inode *inode, struct file *filp)
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;
goto err_unref;
}
/* safe to drop the kref from tty_driver_lookup_tty() */
tty_kref_put(tty);
retval = tty_reopen(tty);
if (retval < 0) {
tty_unlock(tty);

7
drivers/tty/tty_mutex.c
View file

@ -21,10 +21,15 @@ EXPORT_SYMBOL(tty_lock);
int tty_lock_interruptible(struct tty_struct *tty)
{
int ret;
if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
return -EIO;
tty_kref_get(tty);
return mutex_lock_interruptible(&tty->legacy_mutex);
ret = mutex_lock_interruptible(&tty->legacy_mutex);
if (ret)
tty_kref_put(tty);
return ret;
}
void __lockfunc tty_unlock(struct tty_struct *tty)