Re: [RFC PATCH 6.1.y 0/2] bpf: backport scalar not-equal tracking fixes

[Shung-Hsi Yu]

Hi Zhenzhong,

Thanks for looking at the stable kernel branch!

Since this patchset is intended for stable 6.1 I'd suggest to also
include stable@xxxxxxxxxxxxxxx even if this is an RFC (and ideally with
'PATCH stable ...' as subject prefix, but that's just minor), so that
the stable team is aware.

On Tue, Jun 02, 2026 at 02:03:58AM +0800, Zhenzhong Wu wrote:
> Hi BPF maintainers,
> 
> This RFC backports two BPF verifier scalar range-tracking fixes to 6.1.y.
> The series is intended to fix a verifier state-pruning issue where an
> impossible scalar path can be kept while the real success path is pruned.
> 
> This is a verifier scalar range-tracking issue, not a helper-specific
> issue.
> The visible failure is that the verifier can prune the real success
> continuation, which should not be skipped, and keep only an impossible one.
...

This sounds somewhat similar to the issue fixed in "backport of iterator
and callback handling fixes" for stable 6.6[1] by @Eduard. Could you try
to test on the latest stable 6.6.y as well at see if you can reproduce
the issue there?

Also per stable policy[2] we have backport the patches in the series to
6.6 first if we want it in 6.1 anyway.

  When using option 2 or 3 you can ask for your change to be included in specific
  stable series. When doing so, ensure the fix or an equivalent is applicable,
  submitted, or already present in all newer stable trees still supported. This is
  meant to prevent regressions that users might later encounter on updating...

Cheers,
Shung-Hsi Yu

1: https://lore.kernel.org/stable/20240125001554.25287-1-eddyz87@xxxxxxxxx/
2: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html