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Date: Wed, 22 Aug 2007 15:58:33 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Jiri Kosina <jkosina@suse.cz>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       Jakub Jelinek <jakub@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
       Andi Kleen <ak@suse.de>, Kees Cook <kees@outflux.net>,
       Arjan van de Ven <arjan@infradead.org>
Subject: Re: [PATCH] i386 and x86_64: randomize brk()
Message-Id: <20070822155833.5142e588.akpm@linux-foundation.org>
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On Wed, 22 Aug 2007 18:05:01 +0200 (CEST)
Jiri Kosina <jkosina@suse.cz> wrote:

> From: Jiri Kosina <jkosina@suse.cz>
> 
> i386 and x86_64: randomize brk()
> 
> This patch randomizes the location of the heap (brk) for i386 and x86_64. 
> The range is randomized in the range starting at current brk location up 
> to 0x02000000 offset on both architectures. This, together with 
> pie-executable-randomization.patch and 
> pie-executable-randomization-fix.patch, should make the address space 
> randomization on i386 and x86_64 complete (modulo vDSO randomization).
> 
> The code is based on execshield code written by Ingo Molnar.

My main concern right now is to try to stabilise the rc3-mm1 mess, so I
think I'll duck this for now.  

> +#ifdef ARCH_HAS_RANDOMIZE_BRK
> +	if (current->flags & PF_RANDOMIZE)
> +		arch_randomize_brk();
> +#endif

erk, please no.

It'd be better to put

static inline void arch_randomize_brk(void)
{
}

into all the other architecture's elf.h, then lose all the ifdefs.