can: deny filterlist access on non-CAN interfaces

In commit 20dd3850bc "can: Speed up CAN frame
receiption by using ml_priv" the formerly used hlist of receiver lists for
each CAN netdevice has been replaced. 

The hlist content ensured only CAN netdevices to be accessed by the
can_rx_(un)register() functions which accidently dropped away together with
the hlist receiver implementation.

This patch re-introduces the check for CAN netdevices in can_rx_(un)register().

Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/can/af_can.c

@@ -415,6 +415,9 @@ int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
 
 	/* insert new receiver  (dev,canid,mask) -> (func,data) */
 
+	if (dev && dev->type != ARPHRD_CAN)
+		return -ENODEV;
+
 	r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
 	if (!r)
 		return -ENOMEM;
@@ -478,6 +481,9 @@ void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
 	struct hlist_node *next;
 	struct dev_rcv_lists *d;
 
+	if (dev && dev->type != ARPHRD_CAN)
+		return;
+
 	spin_lock(&can_rcvlists_lock);
 
 	d = find_dev_rcv_lists(dev);