* [PATCH 5.10/5.15/6.1/6.6/6.12/6.18] ipvs: skip ipv6 extension headers for csum checks
@ 2026-06-16 6:30 Nazar Kalashnikov
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From: Nazar Kalashnikov @ 2026-06-16 6:30 UTC (permalink / raw)
To: stable, Greg Kroah-Hartman
Cc: Nazar Kalashnikov, Simon Horman, Julian Anastasov,
Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
Phil Sutter, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Venkata Mohan Reddy, Patrick McHardy, Julius Volz,
netdev, lvs-devel, netfilter-devel, coreteam, linux-kernel,
Wensong Zhang, lvc-project
From: Julian Anastasov <ja@ssi.bg>
commit 05cfe9863ef049d98141dc2969eefde72fb07625 upstream.
Protocol checksum validation fails for IPv6 if there are extension
headers before the protocol header. iph->len already contains its
offset, so use it to fix the problem.
Fixes: 2906f66a5682 ("ipvs: SCTP Trasport Loadbalancing Support")
Fixes: 0bbdd42b7efa ("IPVS: Extend protocol DNAT/SNAT and state handlers")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Nazar Kalashnikov <nazarkalashnikov0@gmail.com>
---
Backport fix for CVE-2026-45850
net/netfilter/ipvs/ip_vs_proto_sctp.c | 18 ++++++------------
net/netfilter/ipvs/ip_vs_proto_tcp.c | 21 +++++++--------------
net/netfilter/ipvs/ip_vs_proto_udp.c | 20 +++++++-------------
3 files changed, 20 insertions(+), 39 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
index 83e452916403..63c78a1f3918 100644
--- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
@@ -10,7 +10,8 @@
#include <net/ip_vs.h>
static int
-sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
+sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
+ unsigned int sctphoff);
static int
sctp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
@@ -108,7 +109,7 @@ sctp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
int ret;
/* Some checks before mangling */
- if (!sctp_csum_check(cp->af, skb, pp))
+ if (!sctp_csum_check(cp->af, skb, pp, sctphoff))
return 0;
/* Call application helper if needed */
@@ -156,7 +157,7 @@ sctp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
int ret;
/* Some checks before mangling */
- if (!sctp_csum_check(cp->af, skb, pp))
+ if (!sctp_csum_check(cp->af, skb, pp, sctphoff))
return 0;
/* Call application helper if needed */
@@ -185,19 +186,12 @@ sctp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
}
static int
-sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
+sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
+ unsigned int sctphoff)
{
- unsigned int sctphoff;
struct sctphdr *sh;
__le32 cmp, val;
-#ifdef CONFIG_IP_VS_IPV6
- if (af == AF_INET6)
- sctphoff = sizeof(struct ipv6hdr);
- else
-#endif
- sctphoff = ip_hdrlen(skb);
-
sh = (struct sctphdr *)(skb->data + sctphoff);
cmp = sh->checksum;
val = sctp_compute_cksum(skb, sctphoff);
diff --git a/net/netfilter/ipvs/ip_vs_proto_tcp.c b/net/netfilter/ipvs/ip_vs_proto_tcp.c
index 7da51390cea6..ede4fa3b63f5 100644
--- a/net/netfilter/ipvs/ip_vs_proto_tcp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_tcp.c
@@ -29,7 +29,8 @@
#include <net/ip_vs.h>
static int
-tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
+tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
+ unsigned int tcphoff);
static int
tcp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
@@ -166,7 +167,7 @@ tcp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
int ret;
/* Some checks before mangling */
- if (!tcp_csum_check(cp->af, skb, pp))
+ if (!tcp_csum_check(cp->af, skb, pp, tcphoff))
return 0;
/* Call application helper if needed */
@@ -244,7 +245,7 @@ tcp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
int ret;
/* Some checks before mangling */
- if (!tcp_csum_check(cp->af, skb, pp))
+ if (!tcp_csum_check(cp->af, skb, pp, tcphoff))
return 0;
/*
@@ -301,17 +302,9 @@ tcp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
static int
-tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
+tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
+ unsigned int tcphoff)
{
- unsigned int tcphoff;
-
-#ifdef CONFIG_IP_VS_IPV6
- if (af == AF_INET6)
- tcphoff = sizeof(struct ipv6hdr);
- else
-#endif
- tcphoff = ip_hdrlen(skb);
-
switch (skb->ip_summed) {
case CHECKSUM_NONE:
skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
@@ -322,7 +315,7 @@ tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
&ipv6_hdr(skb)->daddr,
skb->len - tcphoff,
- ipv6_hdr(skb)->nexthdr,
+ IPPROTO_TCP,
skb->csum)) {
IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
"Failed checksum for");
diff --git a/net/netfilter/ipvs/ip_vs_proto_udp.c b/net/netfilter/ipvs/ip_vs_proto_udp.c
index 68260d91c988..ffbebda547fc 100644
--- a/net/netfilter/ipvs/ip_vs_proto_udp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_udp.c
@@ -25,7 +25,8 @@
#include <net/ip6_checksum.h>
static int
-udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
+udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
+ unsigned int udphoff);
static int
udp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
@@ -155,7 +156,7 @@ udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
int ret;
/* Some checks before mangling */
- if (!udp_csum_check(cp->af, skb, pp))
+ if (!udp_csum_check(cp->af, skb, pp, udphoff))
return 0;
/*
@@ -238,7 +239,7 @@ udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
int ret;
/* Some checks before mangling */
- if (!udp_csum_check(cp->af, skb, pp))
+ if (!udp_csum_check(cp->af, skb, pp, udphoff))
return 0;
/*
@@ -297,17 +298,10 @@ udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
static int
-udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
+udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
+ unsigned int udphoff)
{
struct udphdr _udph, *uh;
- unsigned int udphoff;
-
-#ifdef CONFIG_IP_VS_IPV6
- if (af == AF_INET6)
- udphoff = sizeof(struct ipv6hdr);
- else
-#endif
- udphoff = ip_hdrlen(skb);
uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
if (uh == NULL)
@@ -325,7 +319,7 @@ udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
&ipv6_hdr(skb)->daddr,
skb->len - udphoff,
- ipv6_hdr(skb)->nexthdr,
+ IPPROTO_UDP,
skb->csum)) {
IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
"Failed checksum for");
--
2.47.3
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