From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>
Cc: Theodor Arsenij Larionov-Trichkine <theodorlarionov@gmail.com>,
Phil Sutter <phil@nwl.cc>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org
Subject: Re: [BUG] netfilter: nft_fib: NULL-ptr-deref (GPF) in nft_fib6_eval on netdev egress hook
Date: Thu, 25 Jun 2026 00:23:01 +0200 [thread overview]
Message-ID: <ajxYxVLUjknoL2fg@chamomile> (raw)
In-Reply-To: <ajw7y1y7E8yyasOy@strlen.de>
On Wed, Jun 24, 2026 at 10:19:23PM +0200, Florian Westphal wrote:
> Theodor Arsenij Larionov-Trichkine <theodorlarionov@gmail.com> wrote:
> > A `fib' expression in a netdev `egress' base chain dereferences the input
> > device nft_in(pkt), which is NULL on the transmit path, so any IPv6 packet
> > leaving the chain's device hits a GPF / KASAN NULL-ptr-deref. An unprivileged
> > user can set this up in a user+net namespace.
>
> Please just send a patch to disable fib on egress.
I'd suggest nft_fib_netdev needs a nft_fib_netdev_validate().
And nft_fib_validate() need to be restricted to NFPROTO_IPV4, _IPV6
and _INET from ctx->family PoV.
next prev parent reply other threads:[~2026-06-24 22:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-24 19:04 [BUG] netfilter: nft_fib: NULL-ptr-deref (GPF) in nft_fib6_eval on netdev egress hook Theodor Arsenij Larionov-Trichkine
2026-06-24 20:19 ` Florian Westphal
2026-06-24 22:23 ` Pablo Neira Ayuso [this message]
2026-06-24 23:47 ` Florian Westphal
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