can: add missing socket check in can/raw release

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

commit 10022a6c66e199d8f61d9044543f38785713cbbd upstream.

v2: added space after 'if' according code style.

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

Thanks to Dave Jones pointing at this issue in net/can/bcm.c

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/net/can/raw.c b/net/can/raw.c
index 883e9d7..241b2b6 100644 (file)
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -305,7 +305,12 @@ static int raw_init(struct sock *sk)
 static int raw_release(struct socket *sock)
 {
        struct sock *sk = sock->sk;
-       struct raw_sock *ro = raw_sk(sk);
+       struct raw_sock *ro;
+
+       if (!sk)
+               return 0;
+
+       ro = raw_sk(sk);
 
        unregister_netdevice_notifier(&ro->notifier);