[NETFILTER] ctnetlink: Fix oops when no ICMP ID info in message

This patch fixes an userspace triggered oops. If there is no ICMP_ID
info the reference to attr will be NULL.
Signed-off-by: NKrzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NHarald Welte <laforge@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_conntrack_proto_icmp.c

@@ -296,7 +296,8 @@ static int icmp_nfattr_to_tuple(struct nfattr *tb[],
 				struct ip_conntrack_tuple *tuple)
 {
 	if (!tb[CTA_PROTO_ICMP_TYPE-1]
-	    || !tb[CTA_PROTO_ICMP_CODE-1])
+	    || !tb[CTA_PROTO_ICMP_CODE-1]
+	    || !tb[CTA_PROTO_ICMP_ID-1])
 		return -1;
 
 	tuple->dst.u.icmp.type =