linux-kernel - Re: kmemleak splat on copy

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Message-ID: <CAB=NE6UHyeo05OLcAfTCX9qcAAzdLxkShiSjUiEjAHF30oaQdQ@mail.gmail.com>
Date:   Fri, 17 Feb 2017 09:23:43 -0800
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Mateusz Guzik <mguzik@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: kmemleak splat on copy_process()

On Fri, Feb 17, 2017 at 9:07 AM, Andy Lutomirski <luto@...capital.net> wrote:
> But maybe
> there really is a race in which a kmemleak check right in the middle
> of duplicating the task struct really can't see the stack pointer.

Funny, but it was actually using kmemleak how I can easily reproduce:

To reproduce the kmemleak splat:

echo clear >  /sys/kernel/debug/kmemleak
echo scan >  /sys/kernel/debug/kmemleak
cat /sys/kernel/debug/kmemleak

Try that.

 Luis