linux-kernel - Re: [Regression] hangs caused by commit 3202fa62fb (slub: relocate freelist pointer to middle of object)

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Date:   Tue, 21 Jul 2020 12:00:36 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        amd-gfx@...ts.freedesktop.org, Duncan <1i5t5.duncan@....net>,
        Anthony Ruhier <anthony.ruhier@...il.com>,
        Vinicius <mphantomx@...oo.com.br>,
        Thorsten Leemhuis <regressions@...mhuis.info>
Subject: Re: [Regression] hangs caused by commit 3202fa62fb (slub: relocate
 freelist pointer to middle of object)

On Tue, Jul 21, 2020 at 04:55:12PM +0200, Paul Menzel wrote:
> No idea, if you are aware of it yet, but three people verified that commit
> 3202fa62fb (slub: relocate freelist pointer to middle of object) causes a
> regression on AMD hardware [1].

Hi, thanks for emailing; I don't get bugzilla notifications, so I hadn't
seen this yet.

> It’d be great, if you took a look, and advised if this commit (and
> follow-ups) should be reverted, until the issue is analyzed.

There have been a number of fixes to that commit (which I see are
mentioned in a quick skim of the bug), but they've mostly been around
additional slab debugging features. If it's causing a problem outside
of that, my instinct would be there might be a use-after-free happening,
but I'll go read the bug more closely now, and comment there (or here,
if needed).

Thanks!

-- 
Kees Cook