linux-kernel - Re: [PATCH v4] x86: increase MIN_GAP to include randomized stack

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Message-ID: <4AA98BBE.20407@zytor.com>
Date:	Thu, 10 Sep 2009 16:29:02 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jiri Kosina <jkosina@...e.cz>
CC:	Michal Hocko <mhocko@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v4] x86: increase MIN_GAP to include randomized stack

On 09/10/2009 04:14 PM, Jiri Kosina wrote:
> On Tue, 8 Sep 2009, Jiri Kosina wrote:
> 
>>> Currently we are not including randomized stack size when calculating
>>> mmap_base address in arch_pick_mmap_layout for topdown case. This might
>>> cause that mmap_base starts in the stack reserved area because stack is
>>> randomized by 1GB for 64b (8MB for 32b) and the minimum gap is 128MB.
>>>
>>> If the stack really grows down to mmap_base then we can get silent mmap
>>> region overwrite by the stack values.
>>>
>>> Let's include maximum stack randomization size into MIN_GAP which is
>>> used as the low bound for the gap in mmap.
>>>
>>> Signed-off-by: Michal Hocko <mhocko@...e.cz>
>>
>> Acked-by: Jiri Kosina <jkosina@...e.cz>
>>
>> Ingo, could you please consider applying this?
> 
> Any comments about this patch please? (aka. "ping") :)
> 

Looks right to me... I'll apply it and see how it does.

	-hpa

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