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

From: H. Peter Anvin
Date: Thu Sep 10 2009 - 19:31:11 EST


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@xxxxxxx>
>>
>> Acked-by: Jiri Kosina <jkosina@xxxxxxx>
>>
>> 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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