netdev - [PATCH net] udp: call skb_orphan() before skb_attempt_defer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260105093630.1976085-1-edumazet@google.com>
Date: Mon,  5 Jan 2026 09:36:30 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Florian Westphal <fw@...len.de>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>, 
	syzbot+3e68572cf2286ce5ebe9@...kaller.appspotmail.com
Subject: [PATCH net] udp: call skb_orphan() before skb_attempt_defer_free()

Standard UDP receive path does not use skb->destructor.

But skmsg layer does use it, since it calls skb_set_owner_sk_safe()
from udp_read_skb().

This then triggers this warning in skb_attempt_defer_free():

    DEBUG_NET_WARN_ON_ONCE(skb->destructor);

We must call skb_orphan() to fix this issue.

Fixes: 6471658dc66c ("udp: use skb_attempt_defer_free()")
Reported-by: syzbot+3e68572cf2286ce5ebe9@...kaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/695b83bd.050a0220.1c9965.002b.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/udp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ffe074cb5865..ee63af0ef42c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1851,6 +1851,7 @@ void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len)
 		sk_peek_offset_bwd(sk, len);
 
 	if (!skb_shared(skb)) {
+		skb_orphan(skb);
 		skb_attempt_defer_free(skb);
 		return;
 	}
-- 
2.52.0.351.gbe84eed79e-goog