netfilter: xt_conntrack: warn about use in raw table

nfct happens to run after the raw table only.
Signed-off-by: NJan Engelhardt <jengelh@medozas.de>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

net/netfilter/xt_conntrack.c

@@ -272,6 +272,11 @@ static int conntrack_mt_check(const struct xt_mtchk_param *par)
 {
 	int ret;
 
+	if (strcmp(par->table, "raw") == 0) {
+		pr_info("state is undetermined at the time of raw table\n");
+		return -EINVAL;
+	}
+
 	ret = nf_ct_l3proto_try_module_get(par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",