From: Shung-Hsi Yu <shung-hsi.yu@suse.com>
To: Yiyang Chen <chenyy23@mails.tsinghua.edu.cn>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
John Fastabend <john.fastabend@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v3 1/3] bpf: Preserve pointer state for commuted arithmetic
Date: Thu, 23 Jul 2026 11:45:26 +0800 [thread overview]
Message-ID: <amGN9sUvWFi3xfle@u94a> (raw)
In-Reply-To: <004a83de52a36e9f3acd6c3fa2d0dfd0a013460d.1784696372.git.chenyy23@mails.tsinghua.edu.cn>
Oops, missed there was already v3 yesterday. Reposting comments here.
On Wed, Jul 22, 2026 at 05:27:31AM +0000, Yiyang Chen wrote:
> When scalar += pointer is handled in adjust_ptr_min_max_vals(), the
> destination register inherits the pointer state from the source pointer.
> Copying only selected fields is fragile because pointer provenance is
> tracked by several bpf_reg_state fields.
>
> Use verifier-env scratch storage to preserve the scalar operand while
> replacing the destination with the full pointer state. This preserves the
> frame number for PTR_TO_STACK registers and keeps parent identity fields
> consistent.
>
> Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Nit: This doesn't look right. Without bpf2bpf there is just one frame,
hence there isn't a bug at this point. I think the commit f4d7e40a5b71
("bpf: introduce function calls (verification)") the you mentioned in v1
should be used here instead.
[...]
next prev parent reply other threads:[~2026-07-23 3:45 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-22 5:27 [PATCH bpf-next v3 0/3] bpf: Preserve pointer state for commuted arithmetic Yiyang Chen
2026-07-22 5:27 ` [PATCH bpf-next v3 1/3] " Yiyang Chen
2026-07-23 3:45 ` Shung-Hsi Yu [this message]
2026-07-23 4:25 ` Shung-Hsi Yu
2026-07-23 17:35 ` Eduard Zingerman
2026-07-23 17:57 ` Eduard Zingerman
2026-07-23 21:07 ` Eduard Zingerman
2026-07-24 3:05 ` Shung-Hsi Yu
2026-07-24 5:07 ` Eduard Zingerman
2026-07-22 5:27 ` [PATCH bpf-next v3 2/3] bpf: Propagate untrusted pointer state in " Yiyang Chen
2026-07-22 5:27 ` [PATCH bpf-next v3 3/3] selftests/bpf: Cover commuted pointer state propagation Yiyang Chen
2026-07-22 5:34 ` sashiko-bot
2026-07-23 21:18 ` Eduard Zingerman
2026-07-22 11:38 ` [PATCH bpf-next v3 0/3] bpf: Preserve pointer state for commuted arithmetic Daniel Wade
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