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linux/net/ax25
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Duoming Zhou 71171ac8eb ax25: Fix NULL pointer dereference in ax25_kill_by_device 
When two ax25 devices attempted to establish connection, the requester use ax25_create(),
ax25_bind() and ax25_connect() to initiate connection. The receiver use ax25_rcv() to
accept connection and use ax25_create_cb() in ax25_rcv() to create ax25_cb, but the
ax25_cb->sk is NULL. When the receiver is detaching, a NULL pointer dereference bug
caused by sock_hold(sk) in ax25_kill_by_device() will happen. The corresponding
fail log is shown below:

===============================================================
BUG: KASAN: null-ptr-deref in ax25_device_event+0xfd/0x290
Call Trace:
...
ax25_device_event+0xfd/0x290
raw_notifier_call_chain+0x5e/0x70
dev_close_many+0x174/0x220
unregister_netdevice_many+0x1f7/0xa60
unregister_netdevice_queue+0x12f/0x170
unregister_netdev+0x13/0x20
mkiss_close+0xcd/0x140
tty_ldisc_release+0xc0/0x220
tty_release_struct+0x17/0xa0
tty_release+0x62d/0x670
...

This patch add condition check in ax25_kill_by_device(). If s->sk is
NULL, it will goto if branch to kill device.

Fixes: 4e0f718daf ("ax25: improve the incomplete fix to avoid UAF and NPD bugs")
Reported-by: Thomas Osterried <thomas@osterried.de>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-09 12:45:02 +00:00
..
af_ax25.c ax25: Fix NULL pointer dereference in ax25_kill_by_device 2022-03-09 12:45:02 +00:00
ax25_addr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_dev.c ax25: fix reference count leaks of ax25_dev 2022-02-03 14:20:36 -08:00
ax25_ds_in.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_ds_subr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_ds_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_iface.c ax25: constify dev_addr passing 2021-10-13 09:40:45 -07:00
ax25_in.c ax25: constify dev_addr passing 2021-10-13 09:40:45 -07:00
ax25_ip.c ax25: use skb_expand_head 2021-08-03 11:21:39 +01:00
ax25_out.c ax25: constify dev_addr passing 2021-10-13 09:40:45 -07:00
ax25_route.c ax25: fix reference count leaks of ax25_dev 2022-02-03 14:20:36 -08:00
ax25_std_in.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_std_subr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_std_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_subr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ax25_uid.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
Kconfig AX.25 Kconfig: Replace HTTP links with HTTPS ones 2020-07-13 12:34:06 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sysctl_net_ax25.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00