From: Shung-Hsi Yu <shung-hsi.yu@suse.com>
To: 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>,
Daniel Wade <danjwade95@gmail.com>,
bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf v4 2/4] bpf: Preserve pointer state for commuted arithmetic
Date: Thu, 30 Jul 2026 16:25:47 +0800 [thread overview]
Message-ID: <amsJ3D8P46GcsKwp@u94a> (raw)
In-Reply-To: <20260729-c3-035-public-bpf-v4-v4-2-8ee297e2346b@mails.tsinghua.edu.cn>
On Wed, Jul 29, 2026 at 03:18:28PM +0000, Yiyang Chen via B4 Relay wrote:
> From: Yiyang Chen <chenyy23@mails.tsinghua.edu.cn>
>
> 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 the caller's temporary offset register 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: f4d7e40a5b71 ("bpf: introduce function calls (verification)")
> Signed-off-by: Yiyang Chen <chenyy23@mails.tsinghua.edu.cn>
> Tested-by: Daniel Wade <danjwade95@gmail.com>
> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
next prev parent reply other threads:[~2026-07-30 8:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-29 15:18 [PATCH bpf v4 0/4] bpf: Preserve pointer state for commuted arithmetic Yiyang Chen via B4 Relay
2026-07-29 15:18 ` [PATCH bpf v4 1/4] bpf: simplify sanitize_err() signature Yiyang Chen via B4 Relay
2026-07-30 8:22 ` Shung-Hsi Yu
2026-07-29 15:18 ` [PATCH bpf v4 2/4] bpf: Preserve pointer state for commuted arithmetic Yiyang Chen via B4 Relay
2026-07-30 8:25 ` Shung-Hsi Yu [this message]
2026-07-29 15:18 ` [PATCH bpf v4 3/4] bpf: Propagate untrusted pointer state in " Yiyang Chen via B4 Relay
2026-07-29 15:18 ` [PATCH bpf v4 4/4] selftests/bpf: Cover commuted pointer state propagation Yiyang Chen via B4 Relay
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