Re: [PATCH 1/1] ax25: Fix segfault after sock connection timeout

[David Miller]

From: Basil Gunn 
Date: Sat, 14 Jan 2017 12:18:55 -0800

> The ax.25 socket connection timed out & the sock struct has been
> previously taken down ie. sock struct is now a NULL pointer. Checking
> the sock_flag causes the segfault.  Check if the socket struct pointer
> is NULL before checking sock_flag. This segfault is seen in
> timed out netrom connections.
> 
> Please submit to -stable.
> 
> Signed-off-by: Basil Gunn 

This is consistent with the ax25->sk NULL check later in this function.

Applied and queued up for -stable, thanks.

[PATCH 1/1] ax25: Fix segfault after sock connection timeout

[Basil Gunn]

The ax.25 socket connection timed out & the sock struct has been
previously taken down ie. sock struct is now a NULL pointer. Checking
the sock_flag causes the segfault.  Check if the socket struct pointer
is NULL before checking sock_flag. This segfault is seen in
timed out netrom connections.

Please submit to -stable.

Signed-off-by: Basil Gunn 
---

diff --git a/net/ax25/ax25_subr.c b/net/ax25/ax25_subr.c
index 4855d18..038b109 100644
--- a/net/ax25/ax25_subr.c
+++ b/net/ax25/ax25_subr.c
@@ -264,7 +264,7 @@ void ax25_disconnect(ax25_cb *ax25, int reason)
 {
ax25_clear_queues(ax25);

-   if (!sock_flag(ax25->sk, SOCK_DESTROY))
+   if (!ax25->sk || !sock_flag(ax25->sk, SOCK_DESTROY))
ax25_stop_heartbeat(ax25);
ax25_stop_t1timer(ax25);
ax25_stop_t2timer(ax25);