From: Eduard Zingerman <eddyz87@gmail.com>
To: Paul Chaignon <paul.chaignon@gmail.com>
Cc: bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
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 3/4] bpf: Improve ctx access verifier error message
Date: Fri, 01 Aug 2025 09:24:26 -0700 [thread overview]
Message-ID: <85804ed8118715985eb484d3d649b77d754df598.camel@gmail.com> (raw)
In-Reply-To: <aIzpKu2PChlhVGsq@mail.gmail.com>
On Fri, 2025-08-01 at 18:19 +0200, Paul Chaignon wrote:
[...]
> > > @@ -21445,7 +21445,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
> > > &target_size);
> > > if (cnt == 0 || cnt >= INSN_BUF_SIZE ||
> > > (ctx_field_size && !target_size)) {
> > > - verifier_bug(env, "error during ctx access conversion");
> > > + verifier_bug(env, "error during ctx access conversion (%d)", cnt);
> >
> > Nit: maybe print the rest of the fields as well?
>
> I considered it but didn't want to unnecessarily bloat the message.
> Knowing cnt is enough to know which of the three conditions is true. If
> the last one is true, then knowing the values of ctx_field_size and
> target_size doesn't really help us because the issue is just that one is
> set (ctx_field_size in _is_valid_access) while the other wasn't
> (target_size in _convert_ctx_accesses). That indicates a mismatch
> between the two functions for that particular program type.
Ack, makes sense. Thank you for explaining.
next prev parent reply other threads:[~2025-08-01 16:24 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 [this message]
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 ` [PATCH bpf 1/4] bpf: Check flow_dissector ctx accesses are aligned Yonghong Song
2025-08-01 16:04 ` Eduard Zingerman
2025-08-01 16:30 ` patchwork-bot+netdevbpf
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