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| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-03-08 16:12:23 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-03-09 12:45:02 +0000 |
| commit | 71171ac8eb34ce7fe6b3267dce27c313ab3cb3ac (patch) | |
| tree | fb7c10dd2acfaf035b19cd8fdd828e75658e286c /net/ax25 | |
| parent | c9ffa3e2bc451816ce0295e40063514fabf2bd36 (diff) | |
| download | linux-71171ac8eb34ce7fe6b3267dce27c313ab3cb3ac.tar.bz2 | |
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: 4e0f718daf97 ("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>
Diffstat (limited to 'net/ax25')
| -rw-r--r-- | net/ax25/af_ax25.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index d53cbb4e2503..6bd097180772 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -87,6 +87,13 @@ again: ax25_for_each(s, &ax25_list) { if (s->ax25_dev == ax25_dev) { sk = s->sk; + if (!sk) { + spin_unlock_bh(&ax25_list_lock); + s->ax25_dev = NULL; + ax25_disconnect(s, ENETUNREACH); + spin_lock_bh(&ax25_list_lock); + goto again; + } sock_hold(sk); spin_unlock_bh(&ax25_list_lock); lock_sock(sk); |