diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-05-30 23:21:58 +0800 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2022-06-02 10:37:57 +0200 |
| commit | 7d8a3a477b3e25ada8dc71d22048c2ea417209a0 (patch) | |
| tree | 025a2a93fe99c26fa80090c2aed7a3e66114def0 /net/ax25/ax25_dev.c | |
| parent | 9f4fc18bf285f20c1498f8fcfb586fa70a070fb5 (diff) | |
ax25: Fix ax25 session cleanup problems
There are session cleanup problems in ax25_release() and
ax25_disconnect(). If we setup a session and then disconnect,
the disconnected session is still in "LISTENING" state that
is shown below.
Active AX.25 sockets
Dest Source Device State Vr/Vs Send-Q Recv-Q
DL9SAU-4 DL9SAU-3 ??? LISTENING 000/000 0 0
DL9SAU-3 DL9SAU-4 ??? LISTENING 000/000 0 0
The first reason is caused by del_timer_sync() in ax25_release().
The timers of ax25 are used for correct session cleanup. If we use
ax25_release() to close ax25 sessions and ax25_dev is not null,
the del_timer_sync() functions in ax25_release() will execute.
As a result, the sessions could not be cleaned up correctly,
because the timers have stopped.
In order to solve this problem, this patch adds a device_up flag
in ax25_dev in order to judge whether the device is up. If there
are sessions to be cleaned up, the del_timer_sync() in
ax25_release() will not execute. What's more, we add ax25_cb_del()
in ax25_kill_by_device(), because the timers have been stopped
and there are no functions that could delete ax25_cb if we do not
call ax25_release(). Finally, we reorder the position of
ax25_list_lock in ax25_cb_del() in order to synchronize among
different functions that call ax25_cb_del().
The second reason is caused by improper check in ax25_disconnect().
The incoming ax25 sessions which ax25->sk is null will close
heartbeat timer, because the check "if(!ax25->sk || ..)" is
satisfied. As a result, the session could not be cleaned up properly.
In order to solve this problem, this patch changes the improper
check to "if(ax25->sk && ..)" in ax25_disconnect().
What`s more, the ax25_disconnect() may be called twice, which is
not necessary. For example, ax25_kill_by_device() calls
ax25_disconnect() and sets ax25->state to AX25_STATE_0, but
ax25_release() calls ax25_disconnect() again.
In order to solve this problem, this patch add a check in
ax25_release(). If the flag of ax25->sk equals to SOCK_DEAD,
the ax25_disconnect() in ax25_release() should not be executed.
Fixes: 82e31755e55f ("ax25: Fix UAF bugs in ax25 timers")
Fixes: 8a367e74c012 ("ax25: Fix segfault after sock connection timeout")
Reported-and-tested-by: Thomas Osterried <thomas@osterried.de>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/20220530152158.108619-1-duoming@zju.edu.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/ax25/ax25_dev.c')
| -rw-r--r-- | net/ax25/ax25_dev.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c index b80fccbac62a..95a76d571c44 100644 --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -62,6 +62,7 @@ void ax25_dev_device_up(struct net_device *dev) ax25_dev->dev = dev; dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC); ax25_dev->forward = NULL; + ax25_dev->device_up = true; ax25_dev->values[AX25_VALUES_IPDEFMODE] = AX25_DEF_IPDEFMODE; ax25_dev->values[AX25_VALUES_AXDEFMODE] = AX25_DEF_AXDEFMODE; |