From: Florian Westphal <fw@strlen.de>
To: netfilter-devel@vger.kernel.org
Cc: bridge@lists.linux.dev, netdev@vger.kernel.org,
Pablo Neira Ayuso <pablo@netfilter.org>,
Nikolay Aleksandrov <razor@blackwall.org>,
Ido Schimmel <idosch@nvidia.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Sabrina Dubroca <sd@queasysnail.net>, Phil Sutter <phil@nwl.cc>,
Simon Horman <horms@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [BUG] net/bridge: out-of-bounds in br_forward()
Date: Thu, 27 Aug 2026 16:29:28 +0200 [thread overview]
Message-ID: <apBJyKJ7zs4kUmpd@strlen.de> (raw)
In-Reply-To: <fai12uKS5302YnCQV4E3zlDqcsAS5aGcMutS@bugs.sh>
co <co+63bad23bb3b4cd85@bugs.sh> wrote:
> We found a bug reachable in:
>
> path net/bridge/netfilter
> crash out-of-bounds in br_forward()
> commit 7b5344954050 ("Merge tag 'nf-26-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf")
I'm looking into these reports, I think this is the same
underlying bug as the other report; a variant of
ccb9fd4b8753 ("netfilter: revalidate bridge ports")
That bug uses nfnetlink_queue for RCU escape, the other two reports
use defrag engine.
And sure, its br_netfilter again -- I think we will have to consider
removing it even though it will break existing setups.
As a compromise, I suggest to reject br_netfilter in user namespaces,
i.e. call_iptables cannot be enabled anymore unless you have
CAP_NET_ADMIN in init net.
next prev parent reply other threads:[~2026-08-27 14:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-27 12:43 [BUG] net/bridge: out-of-bounds in br_forward() co
2026-08-27 14:29 ` Florian Westphal [this message]
2026-08-27 14:35 ` Nikolay Aleksandrov
2026-08-27 14:54 ` Pablo Neira Ayuso
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