From: Eric Dumazet <edumazet@google.com>
Date: Thu, 16 Apr 2026 10:35:05 +0000 (+0000)
Subject: ipv6: fix possible UAF in icmpv6_rcv()
X-Git-Tag: v7.1-rc1~36^2~57
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=f996edd7615e686ada141b7f3395025729ff8ccb;p=thirdparty%2Fkernel%2Flinux.git

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 <edumazet@google.com>
Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Reviewed-by: Joe Damato <joe@dama.to>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260416103505.2380753-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

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.