linux-kernel - Re: [PATCH 09/12] x86/process: Pin the target stack in get

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Date:   Sat, 17 Sep 2016 04:00:51 +0200
From:   Jann Horn <jann@...jh.net>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     x86@...nel.org, Borislav Petkov <bp@...en8.de>,
        linux-kernel@...r.kernel.org, Brian Gerst <brgerst@...il.com>
Subject: Re: [PATCH 09/12] x86/process: Pin the target stack in get_wchan()

On Tue, Sep 13, 2016 at 02:29:29PM -0700, Andy Lutomirski wrote:
> This will prevent a crash if get_wchan() runs after the task stack
> is freed.

I think I found some more stuff. Have a look at KSTK_EIP() and KSTK_ESP(), I think
they read from the saved userspace registers area at the top of the kernel stack?

Used on remote processes in:
  vma_is_stack_for_task() (via /proc/$pid/maps)
  do_task_stat() (/proc/$pid/stat)

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