can: af_can: Fix error path of can_init()

commit c5a3aed1 upstream.

This patch add error path for can_init() to avoid possible crash if some
error occurs.

Fixes: 0d66548a ("[CAN]: Add PF_CAN core module")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[bwh: Backported to 3.16:
 - af_can doesn't register any pernet_operations
 - It does start a global timer and add procfs entries that need to be
   cleaned up on the error path]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/can/af_can.c

@@ -899,6 +899,8 @@ static struct notifier_block can_netdev_notifier __read_mostly = {
 
 static __init int can_init(void)
 {
+	int err;
+
 	/* check for correct padding to be able to use the structs similarly */
 	BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
 		     offsetof(struct canfd_frame, len) ||
@@ -924,12 +926,29 @@ static __init int can_init(void)
 	can_init_proc();
 
 	/* protocol register */
-	sock_register(&can_family_ops);
-	register_netdevice_notifier(&can_netdev_notifier);
+	err = sock_register(&can_family_ops);
+	if (err)
+		goto out_sock;
+	err = register_netdevice_notifier(&can_netdev_notifier);
+	if (err)
+		goto out_notifier;
+
 	dev_add_pack(&can_packet);
 	dev_add_pack(&canfd_packet);
 
 	return 0;
+
+out_notifier:
+	sock_unregister(PF_CAN);
+out_sock:
+	kmem_cache_destroy(rcv_cache);
+
+	if (stats_timer)
+		del_timer_sync(&can_stattimer);
+
+	can_remove_proc();
+
+	return err;
 }
 
 static __exit void can_exit(void)