From: Yonghong Song <yonghong.song@linux.dev>
To: Paul Chaignon <paul.chaignon@gmail.com>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
netfilter-devel@vger.kernel.org,
Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Petar Penkov <ppenkov@google.com>,
Florian Westphal <fw@strlen.de>
Subject: Re: [PATCH bpf 1/4] bpf: Check flow_dissector ctx accesses are aligned
Date: Fri, 1 Aug 2025 08:52:48 -0700 [thread overview]
Message-ID: <a8e756ca-e9f7-4c56-bd39-3f71e4be9528@linux.dev> (raw)
In-Reply-To: <cc1b036be484c99be45eddf48bd78cc6f72839b1.1754039605.git.paul.chaignon@gmail.com>
On 8/1/25 2:47 AM, Paul Chaignon wrote:
> flow_dissector_is_valid_access doesn't check that the context access is
> aligned. As a consequence, an unaligned access within one of the exposed
> field is considered valid and later rejected by
> flow_dissector_convert_ctx_access when we try to convert it.
>
> The later rejection is problematic because it's reported as a verifier
> bug with a kernel warning and doesn't point to the right instruction in
> verifier logs.
>
> Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook")
> Reported-by: syzbot+ccac90e482b2a81d74aa@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=ccac90e482b2a81d74aa
> Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
next prev parent reply other threads:[~2025-08-01 15:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-01 9:47 [PATCH bpf 1/4] bpf: Check flow_dissector ctx accesses are aligned Paul Chaignon
2025-08-01 9:48 ` [PATCH bpf 2/4] bpf: Check netfilter " Paul Chaignon
2025-08-01 15:54 ` Yonghong Song
2025-08-01 16:06 ` Eduard Zingerman
2025-08-01 9:49 ` [PATCH bpf 3/4] bpf: Improve ctx access verifier error message Paul Chaignon
2025-08-01 16:09 ` Eduard Zingerman
2025-08-01 16:19 ` Paul Chaignon
2025-08-01 16:24 ` Eduard Zingerman
2025-08-01 16:30 ` Yonghong Song
2025-08-01 21:47 ` Alexei Starovoitov
2025-08-02 0:00 ` Yonghong Song
2025-08-01 9:49 ` [PATCH bpf 4/4] selftests/bpf: Test for unaligned flow_dissector ctx access Paul Chaignon
2025-08-01 16:17 ` Eduard Zingerman
2025-08-01 16:33 ` Yonghong Song
2025-08-01 15:52 ` Yonghong Song [this message]
2025-08-01 16:04 ` [PATCH bpf 1/4] bpf: Check flow_dissector ctx accesses are aligned Eduard Zingerman
2025-08-01 16:30 ` patchwork-bot+netdevbpf
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