tipc: eliminate potential memory leak

In the function tipc_sk_mcast_rcv() we call refcount_dec(&skb->users)
on received sk_buffers. Since the reference counter might hit zero at
this point, we have a potential memory leak.

We fix this by replacing refcount_dec() with kfree_skb().
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/tipc/socket.c

@@ -1140,7 +1140,7 @@ void tipc_sk_mcast_rcv(struct net *net, struct sk_buff_head *arrvq,
 				__skb_dequeue(arrvq);
 				__skb_queue_tail(inputq, skb);
 			}
-			refcount_dec(&skb->users);
+			kfree_skb(skb);
 			spin_unlock_bh(&inputq->lock);
 			continue;
 		}