netfilter: nft_flow_offload: IPCB is only valid for ipv4 family

Guard this with a check vs. ipv4, IPCB isn't valid in ipv6 case.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_flow_offload.c

@@ -48,15 +48,20 @@ static int nft_flow_route(const struct nft_pktinfo *pkt,
 	return 0;
 }
 
-static bool nft_flow_offload_skip(struct sk_buff *skb)
+static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
 {
-	struct ip_options *opt  = &(IPCB(skb)->opt);
-
-	if (unlikely(opt->optlen))
-		return true;
 	if (skb_sec_path(skb))
 		return true;
 
+	if (family == NFPROTO_IPV4) {
+		const struct ip_options *opt;
+
+		opt = &(IPCB(skb)->opt);
+
+		if (unlikely(opt->optlen))
+			return true;
+	}
+
 	return false;
 }
 
@@ -74,7 +79,7 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
 	struct nf_conn *ct;
 	int ret;
 
-	if (nft_flow_offload_skip(pkt->skb))
+	if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
 		goto out;
 
 	ct = nf_ct_get(pkt->skb, &ctinfo);