[NETFILTER] ctnetlink: Fix refcount leak ip_conntrack/nat_proto

Remove proto == NULL checking since ip_conntrack_[nat_]proto_find_get
always returns a valid pointer.

Fix missing ip_conntrack_proto_put in some paths.

Signed-off-by: Pablo Neira Ayuso <[e-mail]>
Signed-off-by: Harald Welte <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/netfilter/ip_conntrack_netlink.c

···
 
 	NFA_PUT(skb, CTA_PROTO_NUM, sizeof(u_int8_t), &tuple->dst.protonum);
 
+	/* If no protocol helper is found, this function will return the
+	 * generic protocol helper, so proto won't *ever* be NULL */
 	proto = ip_conntrack_proto_find_get(tuple->dst.protonum);
-	if (likely(proto && proto->tuple_to_nfattr)) {
+	if (likely(proto->tuple_to_nfattr))
 		ret = proto->tuple_to_nfattr(skb, tuple);
-		ip_conntrack_proto_put(proto);
-	}
+	
+	ip_conntrack_proto_put(proto);
 
 	return ret;
 
···
 
 	struct nfattr *nest_proto;
 	int ret;
-	
-	if (!proto || !proto->to_nfattr)
+
+	if (!proto->to_nfattr) {
+		ip_conntrack_proto_put(proto);
 		return 0;
+	}
 	
 	nest_proto = NFA_NEST(skb, CTA_PROTOINFO);
 
···
 
 	proto = ip_conntrack_proto_find_get(tuple->dst.protonum);
 
-	if (likely(proto && proto->nfattr_to_tuple)) {
+	if (likely(proto->nfattr_to_tuple))
 		ret = proto->nfattr_to_tuple(tb, tuple);
-		ip_conntrack_proto_put(proto);
-	}
+	
+	ip_conntrack_proto_put(proto);
 	
 	return ret;
 }
···
 		return -EINVAL;
 
 	npt = ip_nat_proto_find_get(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum);
-	if (!npt)
-		return 0;
 
 	if (!npt->nfattr_to_range) {
 		ip_nat_proto_put(npt);
···
 	nfattr_parse_nested(tb, CTA_PROTOINFO_MAX, attr);
 
 	proto = ip_conntrack_proto_find_get(npt);
-	if (!proto)
-		return -EINVAL;
 
 	if (proto->from_nfattr)
 		err = proto->from_nfattr(tb, ct);