From f996edd7615e686ada141b7f3395025729ff8ccb Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 16 Apr 2026 10:35:05 +0000 Subject: [PATCH] ipv6: fix possible UAF in icmpv6_rcv() Caching saddr and daddr before pskb_pull() is problematic since skb->head can change. Remove these temporary variables: - We only access &ipv6_hdr(skb)->saddr and &ipv6_hdr(skb)->daddr when net_dbg_ratelimited() is called in the slow path. - Avoid potential future misuse after pskb_pull() call. Fixes: 4b3418fba0fe ("ipv6: icmp: include addresses in debug messages") Signed-off-by: Eric Dumazet Reviewed-by: Fernando Fernandez Mancera Reviewed-by: Joe Damato Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260416103505.2380753-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv6/icmp.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index 799d9e9ac45d..efb23807a026 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -1104,7 +1104,6 @@ static int icmpv6_rcv(struct sk_buff *skb) struct net *net = dev_net_rcu(skb->dev); struct net_device *dev = icmp6_dev(skb); struct inet6_dev *idev = __in6_dev_get(dev); - const struct in6_addr *saddr, *daddr; struct icmp6hdr *hdr; u8 type; @@ -1135,12 +1134,10 @@ static int icmpv6_rcv(struct sk_buff *skb) __ICMP6_INC_STATS(dev_net_rcu(dev), idev, ICMP6_MIB_INMSGS); - saddr = &ipv6_hdr(skb)->saddr; - daddr = &ipv6_hdr(skb)->daddr; - if (skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo)) { net_dbg_ratelimited("ICMPv6 checksum failed [%pI6c > %pI6c]\n", - saddr, daddr); + &ipv6_hdr(skb)->saddr, + &ipv6_hdr(skb)->daddr); goto csum_error; } @@ -1220,7 +1217,8 @@ static int icmpv6_rcv(struct sk_buff *skb) break; net_dbg_ratelimited("icmpv6: msg of unknown type [%pI6c > %pI6c]\n", - saddr, daddr); + &ipv6_hdr(skb)->saddr, + &ipv6_hdr(skb)->daddr); /* * error of unknown type.