From: Yizhou Zhao Date: Mon, 6 Jul 2026 10:16:24 +0000 (+0800) Subject: ipvs: use parsed transport offset in SCTP state lookup X-Git-Tag: v7.2-rc3~29^2~3^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2f75c0faa3361b28e36cc0512b3299e163e25789;p=thirdparty%2Fkernel%2Flinux.git ipvs: use parsed transport offset in SCTP state lookup set_sctp_state() reads the SCTP chunk header again in order to drive the IPVS SCTP state table. For IPv6 it computes the offset with sizeof(struct ipv6hdr), while the surrounding IPVS code uses iph.len from ip_vs_fill_iph_skb(), where ipv6_find_hdr() has already skipped extension headers and found the real transport header. This makes the state machine read from the wrong offset for IPv6 SCTP packets that carry extension headers. For example, an INIT packet with an 8-byte destination options header can be scheduled correctly by sctp_conn_schedule(), but set_sctp_state() reads the first byte of the SCTP verification tag as a DATA chunk type. The connection then moves from NONE to ESTABLISHED instead of INIT1, gets the longer established timeout, and updates the active/inactive destination counters incorrectly. This happens even though the SCTP handshake has not completed. Use the parsed transport offset passed down from ip_vs_set_state() for the SCTP chunk-header lookup. For IPv4 and IPv6 packets without extension headers this preserves the existing offset. Fixes: 2906f66a5682 ("ipvs: SCTP Trasport Loadbalancing Support") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/netdev/20260705123040.35755-1-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 --- diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c index 394367b7b388..c67317be17df 100644 --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c @@ -372,20 +372,15 @@ static const char *sctp_state_name(int state) static inline void set_sctp_state(struct ip_vs_proto_data *pd, struct ip_vs_conn *cp, - int direction, const struct sk_buff *skb) + int direction, const struct sk_buff *skb, + unsigned int iph_len) { struct sctp_chunkhdr _sctpch, *sch; unsigned char chunk_type; int event, next_state; - int ihl, cofs; - -#ifdef CONFIG_IP_VS_IPV6 - ihl = cp->af == AF_INET ? ip_hdrlen(skb) : sizeof(struct ipv6hdr); -#else - ihl = ip_hdrlen(skb); -#endif + int cofs; - cofs = ihl + sizeof(struct sctphdr); + cofs = iph_len + sizeof(struct sctphdr); sch = skb_header_pointer(skb, cofs, sizeof(_sctpch), &_sctpch); if (sch == NULL) return; @@ -472,7 +467,7 @@ sctp_state_transition(struct ip_vs_conn *cp, int direction, unsigned int iph_len) { spin_lock_bh(&cp->lock); - set_sctp_state(pd, cp, direction, skb); + set_sctp_state(pd, cp, direction, skb, iph_len); spin_unlock_bh(&cp->lock); }