linux/net/hsr/hsr_main.c
Taehee Yoo de0083c7ed hsr: avoid to create proc file after unregister
When an interface is being deleted, "/proc/net/dev_snmp6/<interface name>"
is deleted.
The function for this is addrconf_ifdown() in the addrconf_notify() and
it is called by notification, which is NETDEV_UNREGISTER.
But, if NETDEV_CHANGEMTU is triggered after NETDEV_UNREGISTER,
this proc file will be created again.
This recreated proc file will be deleted by netdev_wati_allrefs().
Before netdev_wait_allrefs() is called, creating a new HSR interface
routine can be executed and It tries to create a proc file but it will
find an un-deleted proc file.
At this point, it warns about it.

To avoid this situation, it can use ->dellink() instead of
->ndo_uninit() to release resources because ->dellink() is called
before NETDEV_UNREGISTER.
So, a proc file will not be recreated.

Test commands
    ip link add dummy0 type dummy
    ip link add dummy1 type dummy
    ip link set dummy0 mtu 1300

    #SHELL1
    while :
    do
        ip link add hsr0 type hsr slave1 dummy0 slave2 dummy1
    done

    #SHELL2
    while :
    do
        ip link del hsr0
    done

Splat looks like:
[ 9888.980852][ T2752] proc_dir_entry 'dev_snmp6/hsr0' already registered
[ 9888.981797][    C2] WARNING: CPU: 2 PID: 2752 at fs/proc/generic.c:372 proc_register+0x2d5/0x430
[ 9888.981798][    C2] Modules linked in: hsr dummy veth openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6x
[ 9888.981814][    C2] CPU: 2 PID: 2752 Comm: ip Tainted: G        W         5.8.0-rc1+ #616
[ 9888.981815][    C2] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 9888.981816][    C2] RIP: 0010:proc_register+0x2d5/0x430
[ 9888.981818][    C2] Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 65 01 00 00 49 8b b5 e0 00 00 00 48 89 ea 40
[ 9888.981819][    C2] RSP: 0018:ffff8880628dedf0 EFLAGS: 00010286
[ 9888.981821][    C2] RAX: dffffc0000000008 RBX: ffff888028c69170 RCX: ffffffffaae09a62
[ 9888.981822][    C2] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88806c9f75ac
[ 9888.981823][    C2] RBP: ffff888028c693f4 R08: ffffed100d9401bd R09: ffffed100d9401bd
[ 9888.981824][    C2] R10: ffffffffaddf406f R11: 0000000000000001 R12: ffff888028c69308
[ 9888.981825][    C2] R13: ffff8880663584c8 R14: dffffc0000000000 R15: ffffed100518d27e
[ 9888.981827][    C2] FS:  00007f3876b3b0c0(0000) GS:ffff88806c800000(0000) knlGS:0000000000000000
[ 9888.981828][    C2] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9888.981829][    C2] CR2: 00007f387601a8c0 CR3: 000000004101a002 CR4: 00000000000606e0
[ 9888.981830][    C2] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 9888.981831][    C2] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 9888.981832][    C2] Call Trace:
[ 9888.981833][    C2]  ? snmp6_seq_show+0x180/0x180
[ 9888.981834][    C2]  proc_create_single_data+0x7c/0xa0
[ 9888.981835][    C2]  snmp6_register_dev+0xb0/0x130
[ 9888.981836][    C2]  ipv6_add_dev+0x4b7/0xf60
[ 9888.981837][    C2]  addrconf_notify+0x684/0x1ca0
[ 9888.981838][    C2]  ? __mutex_unlock_slowpath+0xd0/0x670
[ 9888.981839][    C2]  ? kasan_unpoison_shadow+0x30/0x40
[ 9888.981840][    C2]  ? wait_for_completion+0x250/0x250
[ 9888.981841][    C2]  ? inet6_ifinfo_notify+0x100/0x100
[ 9888.981842][    C2]  ? dropmon_net_event+0x227/0x410
[ 9888.981843][    C2]  ? notifier_call_chain+0x90/0x160
[ 9888.981844][    C2]  ? inet6_ifinfo_notify+0x100/0x100
[ 9888.981845][    C2]  notifier_call_chain+0x90/0x160
[ 9888.981846][    C2]  register_netdevice+0xbe5/0x1070
[ ... ]

Reported-by: syzbot+1d51c8b74efa4c44adeb@syzkaller.appspotmail.com
Fixes: e0a4b99773 ("hsr: use upper/lower device infrastructure")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-06-22 20:42:23 -07:00

158 lines
3.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright 2011-2014 Autronica Fire and Security AS
*
* Author(s):
* 2011-2014 Arvid Brodin, arvid.brodin@alten.se
*/
#include <linux/netdevice.h>
#include <net/rtnetlink.h>
#include <linux/rculist.h>
#include <linux/timer.h>
#include <linux/etherdevice.h>
#include "hsr_main.h"
#include "hsr_device.h"
#include "hsr_netlink.h"
#include "hsr_framereg.h"
#include "hsr_slave.h"
static bool hsr_slave_empty(struct hsr_priv *hsr)
{
struct hsr_port *port;
hsr_for_each_port(hsr, port)
if (port->type != HSR_PT_MASTER)
return false;
return true;
}
static int hsr_netdev_notify(struct notifier_block *nb, unsigned long event,
void *ptr)
{
struct hsr_port *port, *master;
struct net_device *dev;
struct hsr_priv *hsr;
LIST_HEAD(list_kill);
int mtu_max;
int res;
dev = netdev_notifier_info_to_dev(ptr);
port = hsr_port_get_rtnl(dev);
if (!port) {
if (!is_hsr_master(dev))
return NOTIFY_DONE; /* Not an HSR device */
hsr = netdev_priv(dev);
port = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
if (!port) {
/* Resend of notification concerning removed device? */
return NOTIFY_DONE;
}
} else {
hsr = port->hsr;
}
switch (event) {
case NETDEV_UP: /* Administrative state DOWN */
case NETDEV_DOWN: /* Administrative state UP */
case NETDEV_CHANGE: /* Link (carrier) state changes */
hsr_check_carrier_and_operstate(hsr);
break;
case NETDEV_CHANGENAME:
if (is_hsr_master(dev))
hsr_debugfs_rename(dev);
break;
case NETDEV_CHANGEADDR:
if (port->type == HSR_PT_MASTER) {
/* This should not happen since there's no
* ndo_set_mac_address() for HSR devices - i.e. not
* supported.
*/
break;
}
master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
if (port->type == HSR_PT_SLAVE_A) {
ether_addr_copy(master->dev->dev_addr, dev->dev_addr);
call_netdevice_notifiers(NETDEV_CHANGEADDR,
master->dev);
}
/* Make sure we recognize frames from ourselves in hsr_rcv() */
port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
res = hsr_create_self_node(hsr,
master->dev->dev_addr,
port ?
port->dev->dev_addr :
master->dev->dev_addr);
if (res)
netdev_warn(master->dev,
"Could not update HSR node address.\n");
break;
case NETDEV_CHANGEMTU:
if (port->type == HSR_PT_MASTER)
break; /* Handled in ndo_change_mtu() */
mtu_max = hsr_get_max_mtu(port->hsr);
master = hsr_port_get_hsr(port->hsr, HSR_PT_MASTER);
master->dev->mtu = mtu_max;
break;
case NETDEV_UNREGISTER:
if (!is_hsr_master(dev)) {
master = hsr_port_get_hsr(port->hsr, HSR_PT_MASTER);
hsr_del_port(port);
if (hsr_slave_empty(master->hsr)) {
const struct rtnl_link_ops *ops;
ops = master->dev->rtnl_link_ops;
ops->dellink(master->dev, &list_kill);
unregister_netdevice_many(&list_kill);
}
}
break;
case NETDEV_PRE_TYPE_CHANGE:
/* HSR works only on Ethernet devices. Refuse slave to change
* its type.
*/
return NOTIFY_BAD;
}
return NOTIFY_DONE;
}
struct hsr_port *hsr_port_get_hsr(struct hsr_priv *hsr, enum hsr_port_type pt)
{
struct hsr_port *port;
hsr_for_each_port(hsr, port)
if (port->type == pt)
return port;
return NULL;
}
static struct notifier_block hsr_nb = {
.notifier_call = hsr_netdev_notify, /* Slave event notifications */
};
static int __init hsr_init(void)
{
int res;
BUILD_BUG_ON(sizeof(struct hsr_tag) != HSR_HLEN);
register_netdevice_notifier(&hsr_nb);
res = hsr_netlink_init();
return res;
}
static void __exit hsr_exit(void)
{
hsr_netlink_exit();
hsr_debugfs_remove_root();
unregister_netdevice_notifier(&hsr_nb);
}
module_init(hsr_init);
module_exit(hsr_exit);
MODULE_LICENSE("GPL");