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Date: Fri, 11 Mar 2016 08:19:49 -0800
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Subject: Re: [PATCH] x86: Enable full randomization on i386 and X86_32.
From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>, Ingo Molnar <mingo@redhat.com>,
        Hector Marco-Gisbert <hecmargi@upv.es>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        "x86@kernel.org" <x86@kernel.org>,
        Ismael Ripoll Ripoll <iripoll@upv.es>,
        Harvey Harrison <harvey.harrison@gmail.com>
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On Fri, Mar 11, 2016 at 12:53 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Kees Cook <keescook@chromium.org> wrote:
>
>> On Thu, Mar 10, 2016 at 12:53 PM, Arjan van de Ven
>> <arjan@linux.intel.com> wrote:
>> >> Arjan, or other folks, can you remember why x86_32 disabled mmap
>> >> randomization here? There doesn't seem to be a good reason for it that
>> >> I see.
>> >
>> >
>> > for unlimited stack it got really messy with threaded apps.
>>
>> Seems like it'd only cause problems for really really giant processes?
>> (I think it's telling that the other 32-bit archs don't disable ASLR
>> in this case...)
>
> IIRC there was some sort of specific breakage with unlimited stack apps - I don't
> remember the exact details.
>
>> > anyway, I don't mind seeing if this will indeed work, with time running out
>> > where 32 bit is going extinct... in a few years we just won't have enough
>> > testing on this kind of change anymore.
>>
>> Sounds good. Ingo, can you pull this in and we can try it for -next?
>
> Ok, we can certainly try. If there's breakage with old distros then we might need
> to put this behind a legacy Kconfig switch.

Okay, sounds good. Thanks!

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security