> On 2018年9月10日, at 下午11:36, Jiri Benc <jb...@redhat.com> wrote: > > On Mon, 10 Sep 2018 16:25:09 +0800, Haishuang Yan wrote: >> + if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IPV6), >> + offset) < 0) { >> + if (!csum_err) /* ignore csum errors. */ >> + return; >> } > > gre_parse_header stops parsing when csum_err is encountered. Which > means tpi.key is undefined... > >> >> - if (!pskb_may_pull(skb, offset + grehlen)) >> - return; >> ipv6h = (const struct ipv6hdr *)skb->data; >> - greh = (const struct gre_base_hdr *)(skb->data + offset); >> - key = key_off ? *(__be32 *)(skb->data + key_off) : 0; >> - >> t = ip6gre_tunnel_lookup(skb->dev, &ipv6h->daddr, &ipv6h->saddr, >> - key, greh->protocol); >> + tpi.key, tpi.proto); > > ...and can't be used here. > > Jiri > You are right. Thanks for reviewing. So the same problem also arise in ipgre_err code: 187 iph = (const struct iphdr *)(icmp_hdr(skb) + 1); 188 t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags, 189 iph->daddr, iph->saddr, tpi->key); Since csum_err may not be used outside, how about refactoring gre_parse_header function like this: --- a/net/ipv4/gre_demux.c +++ b/net/ipv4/gre_demux.c @@ -86,7 +86,7 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, options = (__be32 *)(greh + 1); if (greh->flags & GRE_CSUM) { - if (skb_checksum_simple_validate(skb)) { + if (csum_err && skb_checksum_simple_validate(skb)) { *csum_err = true; return -EINVAL; } And in gre_err function, we can call gre_parse_header(skb, &tpi, NULL, **) like this: --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -234,11 +234,9 @@ static void gre_err(struct sk_buff *skb, u32 info) struct tnl_ptk_info tpi; bool csum_err = false; - if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP), - iph->ihl * 4) < 0) { - if (!csum_err) /* ignore csum errors. */ + if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IP), + iph->ihl * 4) < 0) return; - }