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From: Zhou Qiuyue <n0ps1edzz@gmail.com>
To: David Laight <david.laight.linux@gmail.com>
Cc: netdev@vger.kernel.org, David Ahern <dsahern@kernel.org>,
	Ido Schimmel <idosch@nvidia.com>,
	David S. Miller <davem@davemloft.net>,
	Eric Dumazet <edumazet@kernel.org>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Simon Horman <horms@kernel.org>,
	Hangbin Liu <hangbin.liu@linux.dev>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH net v2] ipv6: raw: fix use-after-free in rawv6_send_hdrinc()
Date: Sat, 31 Oct 2026 01:38:22 +0800	[thread overview]
Message-ID: <179338190237.9376.13820542101227461550@gmail.com> (raw)
In-Reply-To: <20261030160532.4832d994@pumpkin>

Thanks, David.

Yes, in the redirect case it passes the old rt->dst.dev, while skb->dst
has already been replaced. That changes the NF_HOOK outdev, so it
probably belongs in a separate fix.

A bare rt6i_idev or dst.dev pointer looks unsafe, since dropping the old
route drops the refs they rely on. An explicit hold/put could replace the
RCU lock, but adds per-packet refs, and doesn't avoid the deferred route
free. As far as I can tell, that uses the embedded dst rcu_head; the
temporary rt6 in this path comes from the existing HDRINCL lookup, and v2
doesn't add a new alloc/free there.

I'll test moving the RCU read lock before l3mdev_ip6_out().

  reply	other threads:[~2026-10-30 17:38 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-26  4:48 Zhou Qiuyue
2026-10-26  6:09 ` Hangbin Liu
2026-10-26 15:07   ` Antoine Tenart
2026-10-27  1:38     ` Hangbin Liu
2026-10-27  9:43       ` Antoine Tenart
2026-10-28  1:27         ` Hangbin Liu
2026-10-28 14:37           ` David Ahern
2026-10-28  7:50 ` netdev-bot+sashiko
2026-10-30  9:40 ` patchwork-bot+netdevbpf
2026-10-30 16:05 ` David Laight
2026-10-30 17:38   ` Zhou Qiuyue [this message]
2026-10-30 19:52     ` David Laight

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