Re: [PATCH 6.12 034/244] bpf: Fix u32/s32 bounds when ranges cross min/max boundary

Alexei Starovoitov
2026-04-01T14:32:40Z

On Wed, Apr 1, 2026 at 4:44 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Apr 01, 2026 at 02:22:58PM +0800, Shung-Hsi Yu wrote:
> > Cc Eduard and Paul since they know this change better.
> >
> > On Tue, Mar 31, 2026 at 06:19:44PM +0200, Greg Kroah-Hartman wrote:
> > > 6.12-stable review patch. If anyone has any objections, please let me know.
> > >
> > > ------------------
> > >
> > > From: Eduard Zingerman <eddyz87@gmail.com>
> > >
> > > [ Upstream commit fbc7aef517d8765e4c425d2792409bb9bf2e1f13 ]
> > >
> > > Same as in __reg64_deduce_bounds(), refine s32/u32 ranges
> > > in __reg32_deduce_bounds() in the following situations:
> > ...
> >
> > Hi Greg,
> >
> > This patch is causing the following BPF selftests to fail
> >
> > #222 reg_bounds_crafted
> > #222/27 reg_bounds_crafted/(u64)[0x7fffffffffffffff; 0xffffffff00000000] (s64)<op> 0
> > #222/28 reg_bounds_crafted/(u64)0 (s64)<op> [0x7fffffffffffffff; 0xffffffff00000000]
> > #222/29 reg_bounds_crafted/(u64)[0x7fffffff00000001; 0xffffffff00000000] (s64)<op> 0
> > #222/30 reg_bounds_crafted/(u64)0 (s64)<op> [0x7fffffff00000001; 0xffffffff00000000]
> > #222/59 reg_bounds_crafted/(s64)[0xffffffff00000001; 0] (u64)<op> 0xffffffff00000000
> > #222/60 reg_bounds_crafted/(s64)0xffffffff00000000 (u64)<op> [0xffffffff00000001; 0]
> > #222/79 reg_bounds_crafted/(s64)[S64_MIN; 0] (u64)<op> 0
> > #222/80 reg_bounds_crafted/(s64)0 (u64)<op> [S64_MIN; 0]
> > #262 reg_bounds_rand_consts_s64_u64
> >
> > The failure is caused by the selftests' expectation not aligning to the
> > stable 6.12 behavior. I believe the easier way out is to drop this, then
> > wait for [1] to land and pick it up in stable (or I'll try to backport
> > and send). That should address the root cause of what this patch is
> > trying to workaround.
> >
> > 1: https://lore.kernel.org/bpf/d4fe45f8bd5c6a48efd2ba3b66932bf7eb5aa020.1774025082.git.paul.chaignon@gmail.com/
>
> Now dropped, thanks.

I suggest ignoring the selftest failures.
The patch is necessary for stable and backports.
It's fixing a real issue.