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Date: Thu, 10 Sep 2009 16:29:02 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Jiri Kosina <jkosina@suse.cz>
CC: Michal Hocko <mhocko@suse.cz>, Andrew Morton <akpm@linux-foundation.org>,
       Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v4] x86: increase MIN_GAP to include randomized stack
References: <20090908085328.GD22397@tiehlicka.suse.cz> <1252400515-6866-1-git-send-email-mhocko@suse.cz> <alpine.LNX.2.00.0909081107580.23856@wotan.suse.de> <alpine.LNX.2.00.0909110112470.23856@wotan.suse.de>
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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@suse.cz>
>>
>> Acked-by: Jiri Kosina <jkosina@suse.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