From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Xia Yan <yanxia@cmss.chinamobile.com>, netdev@vger.kernel.org
Cc: dsahern@kernel.org, idosch@nvidia.com, davem@davemloft.net,
edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com,
horms@kernel.org, willemdebruijn.kernel@gmail.com,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
yana06070@163.com, shuah@kernel.org,
linux-kselftest@vger.kernel.org, willemb@google.com,
tpluszz77@gmail.com
Subject: Re: [PATCH net v3 1/2] ipv6: fix cached route reuse for control messages
Date: Mon, 09 Nov 2026 21:33:54 -0500 [thread overview]
Message-ID: <willemdebruijn.kernel.136b3b685931d@gmail.com> (raw)
In-Reply-To: <20261109014400.9025-1-yanxia@cmss.chinamobile.com>
Xia Yan wrote:
> A connected IPv6 UDP or ping socket can reuse its cached route when an
> SO_MARK cmsg requests another mark. A packet can then bypass a prohibit
> rule instead of failing with EACCES.
>
> ip6_sk_dst_lookup_flow() reads the cache even when connected is false.
> UDP clears connected after parsing IP or socket control messages. Ping
> always passes false.
>
> Only read the cache when connected is true. Ordinary connected UDP
> sends keep using the cache. Ping sends do a fresh lookup.
>
> Found during code review of IPv6 UDP route caching. On UML, the same
> connected-socket selftest fails four IPv6 cases before the fix and
> passes all 54 with it.
>
> Fixes: c6af0c227a22 ("ip: support SO_MARK cmsg")
> Suggested-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> Link: https://lore.kernel.org/netdev/willemdebruijn.kernel.1e0038bcc3ef8@gmail.com/
> Cc: stable@vger.kernel.org
> Signed-off-by: Xia Yan <yanxia@cmss.chinamobile.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
next prev parent reply other threads:[~2026-11-10 2:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-09 1:45 [PATCH net v3 1/2] ipv6: fix cached route reuse for control messages Xia Yan
2026-11-09 1:45 ` [PATCH net v3 2/2] selftests: net: exercise SO_MARK on connected sockets Xia Yan
2026-11-10 2:47 ` Willem de Bruijn
2026-11-10 2:33 ` Willem de Bruijn [this message]
2026-11-12 17:00 ` [PATCH net v3 1/2] ipv6: fix cached route reuse for control messages patchwork-bot+netdevbpf
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