linux-kernel - Re: c/r: prctl: Drop VMA flags test on PR_SET_MM

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Date:	Thu, 26 Apr 2012 11:17:08 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: c/r: prctl: Drop VMA flags test on PR_SET_MM_ stack data assignment

On Thu, Apr 26, 2012 at 9:08 AM, Cyrill Gorcunov <gorcunov@...il.com> wrote:
> From: Cyrill Gorcunov <gorcunov@...nvz.org>
>
> With the
>
>  | commit b76437579d1344b612cf1851ae610c636cec7db0
>  | Author: Siddhesh Poyarekar <siddhesh.poyarekar@...il.com>
>  | Date:   Wed Mar 21 16:34:04 2012 -0700
>  |
>  | procfs: mark thread stack correctly in proc/<pid>/maps
>
> the stack allocated via clone() is marked in /proc/<pid>/maps as
> [stack:%d] thus it might be out of the former mm->start_stack/end_stack
> values (and even has some custom VMA flags set). So to be able to
> restore mm->start_stack/end_stack drop vma flags test, but still
> require the undrlied VMA to exist.
>
> As always note this feature is under CONFIG_CHECKPOINT_RESTORE
> and requires CAP_SYS_RESOURCE to be granted.
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>

It'd be nice if there was some sensible per-thread kernel record of
where the stack is expected to be. Regardless:

Acked-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook
Chrome OS Security
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