From: Florian Westphal <fw@strlen.de>
To: Phil Sutter <phil@nwl.cc>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Helen Koike <koike@igalia.com>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-dev@igalia.com
Subject: Re: [PATCH] netfilter: nf_tables: fix use-after-free on ops->dev
Date: Wed, 4 Mar 2026 14:28:24 +0100 [thread overview]
Message-ID: <aagzeEIkk1v4OmJk@strlen.de> (raw)
In-Reply-To: <aagqaq6LNJnrg8eC@orbyte.nwl.cc>
Phil Sutter <phil@nwl.cc> wrote:
> But isn't __nf_unregister_net_hook() still called immediately when
> handling NETDEV_UNREGISTER event? I guess struct nf_hook_ops::dev may
> still be accessed afterwards since ops is RCU-freed. Is Helen's report
> inaccurate in that regard?
Its a red herring.
The device is registered twice. But UNREGISTER only removes ONE
instance.
Then, later, when a different device (same name!) invokes netlink handler,
the walk finds the old, free'd net_device.
I hacked UNREGISTER to handle this: no more splat.
I reverted this change and altered REGISTER to never allow
double-register: no splats.
prev parent reply other threads:[~2026-03-04 13:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-02 21:26 [PATCH] netfilter: nf_tables: fix use-after-free on ops->dev Helen Koike
2026-03-02 23:08 ` Pablo Neira Ayuso
2026-03-03 14:33 ` Helen Koike
2026-03-04 5:32 ` Florian Westphal
2026-03-04 12:26 ` Phil Sutter
2026-03-04 13:38 ` Florian Westphal
2026-03-04 14:59 ` Helen Koike
2026-03-04 12:49 ` Phil Sutter
2026-03-04 13:28 ` Florian Westphal [this message]
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