[NETFILTER]: nfnetlink_queue: fix possible NULL-ptr dereference

Fix NULL-ptr dereference when a config message for a non-existant
queue containing only an NFQA_CFG_PARAMS attribute is received.

Coverity #433

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/nfnetlink_queue.c

@@ -928,8 +928,12 @@ nfqnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
 
 	if (nfqa[NFQA_CFG_PARAMS-1]) {
 		struct nfqnl_msg_config_params *params;
-		params = NFA_DATA(nfqa[NFQA_CFG_PARAMS-1]);
 
+		if (!queue) {
+			ret = -ENOENT;
+			goto out_put;
+		}
+		params = NFA_DATA(nfqa[NFQA_CFG_PARAMS-1]);
 		nfqnl_set_mode(queue, params->copy_mode,
 				ntohl(params->copy_range));
 	}