From: Shung-Hsi Yu <shung-hsi.yu@suse.com>
To: Zhenzhong Wu <jt26wzz@gmail.com>
Cc: stable@vger.kernel.org, Paul Chaignon <paul.chaignon@gmail.com>,
bpf@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, ast@kernel.org,
daniel@iogearbox.net, john.fastabend@gmail.com,
andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
yonghong.song@linux.dev, kpsingh@kernel.org, haoluo@google.com,
jolsa@kernel.org, menglong8.dong@gmail.com, tamird@kernel.org,
eddyz87@gmail.com
Subject: Re: [RFC PATCH 6.1.y 0/2] bpf: backport scalar not-equal tracking fixes
Date: Sat, 6 Jun 2026 17:19:04 +0800 [thread overview]
Message-ID: <aiPlO4a8QnMFBqc2@u94a> (raw)
In-Reply-To: <CALgi0X=qjiB756FnrYowor26sybA4z2jNCPrjieGcAA52KJS1w@mail.gmail.com>
Just want to send out a quick reply after looking at this.
On Wed, Jun 03, 2026 at 01:25:15AM +0800, Zhenzhong Wu wrote:
> Hi Shung-Hsi,
...
> I ran the suggested checks with the same reproducer, where BAD means the
> program ran and observed the unexpected error, and GOOD means no error was
> observed:
>
> - latest 6.6.y, v6.6.142 (924b4a879cbb): BAD
> - bpf-next at b93c55b4932d: GOOD
> - bpf-next with the d028f87517d6 JNE refinement reverted: still GOOD
>
> So the issue still reproduces on the latest 6.6.y, but d028f87517d6 alone
> does not explain why bpf-next passes. I'll do more narrowing and update the
> candidate backport set accordingly.
...
I think it possibly comes down to commit 4bf79f9be434e ("bpf: Track
equal scalars history on per-instruction level") added in v6.12. Without
that, the precise mark wasn't propogated (for scalars with the same ID),
and that likely made the state comparison (invalidly) go through.
Shung-Hsi
prev parent reply other threads:[~2026-06-06 9:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-01 18:03 [RFC PATCH 6.1.y 0/2] bpf: backport scalar not-equal tracking fixes Zhenzhong Wu
2026-06-01 18:03 ` [RFC PATCH 6.1.y 1/2] bpf: drop knowledge-losing __reg_combine_{32,64}_into_{64,32} logic Zhenzhong Wu
2026-06-01 18:04 ` [RFC PATCH 6.1.y 2/2] bpf: make the verifier tracks the "not equal" for regs Zhenzhong Wu
2026-06-02 5:47 ` [RFC PATCH 6.1.y 0/2] bpf: backport scalar not-equal tracking fixes Shung-Hsi Yu
2026-06-02 6:42 ` Shung-Hsi Yu
2026-06-02 9:17 ` Shung-Hsi Yu
2026-06-02 17:25 ` Zhenzhong Wu
2026-06-06 9:19 ` Shung-Hsi Yu [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=aiPlO4a8QnMFBqc2@u94a \
--to=shung-hsi.yu@suse.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=haoluo@google.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=jt26wzz@gmail.com \
--cc=kpsingh@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.lau@linux.dev \
--cc=menglong8.dong@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=paul.chaignon@gmail.com \
--cc=song@kernel.org \
--cc=stable@vger.kernel.org \
--cc=tamird@kernel.org \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox