diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-04-21 13:24:20 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-27 13:39:46 +0200 |
| commit | cb18d72179bf42a6ccd2b311739017b0ba9bc26e (patch) | |
| tree | 032da95bd78abb9f18470e7d670474595cc315b5 | |
| parent | 1bf1b2a8a2caf9bc0d3cf1aa903a8dcaaa4371d0 (diff) | |
ax25: fix NPD bug in ax25_disconnect
commit 7ec02f5ac8a5be5a3f20611731243dc5e1d9ba10 upstream.
The ax25_disconnect() in ax25_kill_by_device() is not
protected by any locks, thus there is a race condition
between ax25_disconnect() and ax25_destroy_socket().
when ax25->sk is assigned as NULL by ax25_destroy_socket(),
a NULL pointer dereference bug will occur if site (1) or (2)
dereferences ax25->sk.
ax25_kill_by_device() | ax25_release()
ax25_disconnect() | ax25_destroy_socket()
... |
if(ax25->sk != NULL) | ...
... | ax25->sk = NULL;
bh_lock_sock(ax25->sk); //(1) | ...
... |
bh_unlock_sock(ax25->sk); //(2)|
This patch moves ax25_disconnect() into lock_sock(), which can
synchronize with ax25_destroy_socket() in ax25_release().
Fail log:
===============================================================
BUG: kernel NULL pointer dereference, address: 0000000000000088
...
RIP: 0010:_raw_spin_lock+0x7e/0xd0
...
Call Trace:
ax25_disconnect+0xf6/0x220
ax25_device_event+0x187/0x250
raw_notifier_call_chain+0x5e/0x70
dev_close_many+0x17d/0x230
rollback_registered_many+0x1f1/0x950
unregister_netdevice_queue+0x133/0x200
unregister_netdev+0x13/0x20
...
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
[OP: backport to 4.19: adjust context]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ax25/af_ax25.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 6d08b8ef4219..cc0d6b3d5ad7 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -105,8 +105,8 @@ again: dev_put(ax25_dev->dev); ax25_dev_put(ax25_dev); } - release_sock(sk); ax25_disconnect(s, ENETUNREACH); + release_sock(sk); spin_lock_bh(&ax25_list_lock); sock_put(sk); /* The entry could have been deleted from the |