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Date:   Wed, 17 Apr 2019 13:21:48 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     Jitendra Sharma <shajit@codeaurora.org>,
        "Luis R. Rodriguez" <mcgrof@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        linux-arm-msm@vger.kernel.org
Subject: Re: fs/proc: Crash observed in next_tgid (fs/proc/base.c)
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 <CAGXu5jLabRWRdknf_CSBJ316vXYrEUCPTUCsm50WEwdpVNfE3g@mail.gmail.com>
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On 04/16, Kees Cook wrote:
>
> Do you have any hints on how to reproduce this? I assume something is
> missing proper locking or RCU handling,

or we simply have an unbalanced put_task_struct() anywhere else ...

> but I don't see anything
> obvious in the surrounding code yet...

I too do not see anything wrong in proc_pid_readdir() paths

Oleg.