can: Add missing socket check in can/bcm release.

BugLink: http://bugs.launchpad.net/bugs/780546

commit c6914a6f261aca0c9f715f883a353ae7ff51fe83 upstream.

We can get here with a NULL socket argument passed from userspace,
so we need to handle it accordingly.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/net/can/bcm.c b/net/can/bcm.c
index d4cc090..dff4e3d 100644 (file)
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1427,9 +1427,14 @@ static int bcm_init(struct sock *sk)
 static int bcm_release(struct socket *sock)
 {
        struct sock *sk = sock->sk;
-       struct bcm_sock *bo = bcm_sk(sk);
+       struct bcm_sock *bo;
        struct bcm_op *op, *next;
 
+       if (sk == NULL)
+               return 0;
+
+       bo = bcm_sk(sk);
+
        /* remove bcm_ops, timer, rx_unregister(), etc. */
 
        unregister_netdevice_notifier(&bo->notifier);