From 2500fa3958b1ba51c2b065e39db1b04dfa7e23a2 Mon Sep 17 00:00:00 2001 From: Yizhou Zhao Date: Mon, 6 Jul 2026 18:16:23 +0800 Subject: [PATCH] ipvs: use parsed transport offset in TCP state lookup TCP state handling reparses the skb to find the TCP header. For IPv6 it uses sizeof(struct ipv6hdr), while the surrounding IPVS code already parsed the packet with ip_vs_fill_iph_skb() and has the real transport-header offset in iph.len. This makes TCP state handling look at the wrong bytes when an IPv6 packet carries extension headers. Use the parsed transport offset passed down from ip_vs_set_state() when reading the TCP header. For IPv4 and for IPv6 packets without extension headers, the passed offset matches the previous value. Fixes: 0bbdd42b7efa6 ("IPVS: Extend protocol DNAT/SNAT and state handlers") Link: https://lore.kernel.org/netdev/20260705125659.37744-1-zhaoyz24@mails.tsinghua.edu.cn/ Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: Claude Code:GLM-5.2 Signed-off-by: Yizhou Zhao Acked-by: Julian Anastasov Signed-off-by: Florian Westphal --- net/netfilter/ipvs/ip_vs_proto_tcp.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_proto_tcp.c b/net/netfilter/ipvs/ip_vs_proto_tcp.c index 2d3f6aeafe52..f86b763efcc4 100644 --- a/net/netfilter/ipvs/ip_vs_proto_tcp.c +++ b/net/netfilter/ipvs/ip_vs_proto_tcp.c @@ -584,13 +584,7 @@ tcp_state_transition(struct ip_vs_conn *cp, int direction, { struct tcphdr _tcph, *th; -#ifdef CONFIG_IP_VS_IPV6 - int ihl = cp->af == AF_INET ? ip_hdrlen(skb) : sizeof(struct ipv6hdr); -#else - int ihl = ip_hdrlen(skb); -#endif - - th = skb_header_pointer(skb, ihl, sizeof(_tcph), &_tcph); + th = skb_header_pointer(skb, iph_len, sizeof(_tcph), &_tcph); if (th == NULL) return; -- 2.47.3