ipv6-multicast: Fix memory leak in input path.

Have to free the skb before returning if we fail
the fib lookup.
Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6mr.c

@@ -2052,8 +2052,10 @@ int ip6_mr_input(struct sk_buff *skb)
 	int err;
 
 	err = ip6mr_fib_lookup(net, &fl6, &mrt);
-	if (err < 0)
+	if (err < 0) {
+		kfree_skb(skb);
 		return err;
+	}
 
 	read_lock(&mrt_lock);
 	cache = ip6mr_cache_find(mrt,