netfilter: nfnetlink_queue: reject verdict request from different portid

commit 00a3101f upstream.

Like NFQNL_MSG_VERDICT_BATCH do, we should also reject the verdict
request when the portid is not same with the initial portid(maybe
from another process).

Fixes: 97d32cf9 ("netfilter: nfnetlink_queue: batch verdict support")
Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/netfilter/nfnetlink_queue_core.c

@@ -985,10 +985,8 @@ nfqnl_recv_verdict(struct sock *ctnl, struct sk_buff *skb,
 	struct net *net = sock_net(ctnl);
 	struct nfnl_queue_net *q = nfnl_queue_pernet(net);
 
-	queue = instance_lookup(q, queue_num);
-	if (!queue)
-		queue = verdict_instance_lookup(q, queue_num,
-						NETLINK_CB(skb).portid);
+	queue = verdict_instance_lookup(q, queue_num,
+					NETLINK_CB(skb).portid);
 	if (IS_ERR(queue))
 		return PTR_ERR(queue);