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

On Tue, Jun 02, 2026 at 01:47:01PM +0800, Shung-Hsi Yu wrote:
...

On Tue, Jun 02, 2026 at 02:03:58AM +0800, Zhenzhong Wu wrote:

quoted

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?

...

My mistake, the reproducer you had doesn't use iterator or callback, so
probably not fixed in stable 6.6. I'll take a better look at this later
this week.

1: https://lore.kernel.org/stable/20240125001554.25287-1-eddyz87@gmail.com/ (local)
2: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html