diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-02-08 18:40:00 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-02-09 14:55:02 +0300 |
| commit | 7ec02f5ac8a5be5a3f20611731243dc5e1d9ba10 (patch) | |
| tree | e81d40938d51c4a8ed0326df32057ea05c6a7dec | |
| parent | 676b49366a70ea91997585ba8e4577290f5172a5 (diff) | |
| download | linux-7ec02f5ac8a5be5a3f20611731243dc5e1d9ba10.tar.xz | |
ax25: fix NPD bug in ax25_disconnect
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>
| -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 3e49d28824ed..3d87040d1bfc 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -92,8 +92,8 @@ again: lock_sock(sk); s->ax25_dev = NULL; 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 |