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From: Ingo Molnar <mingo@elte.hu>
To: Jiri Kosina <jkosina@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Arjan van de Ven <arjan@infradead.org>,
	Randy Dunlap <randy.dunlap@oracle.com>,
	Hugh Dickins <hugh@veritas.com>, Pavel Machek <pavel@ucw.cz>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Document randomize_va_space and CONFIG_COMPAT_BRK (was Re: [PATCH 2/2] ASLR: add possibility for more fine-grained tweaking)
Date: Thu, 7 Feb 2008 16:01:22 +0100	[thread overview]
Message-ID: <20080207150122.GA10346@elte.hu> (raw)
In-Reply-To: <Pine.LNX.4.64.0802071525520.30955@jikos.suse.cz>


* Jiri Kosina <jkosina@suse.cz> wrote:

> On Thu, 7 Feb 2008, Ingo Molnar wrote:
> 
> > i'm wondering about the following detail: i guess on 64-bit x86 
> > kernels we could default to !CONFIG_COMPAT_BRK? In 1997 there was no 
> > 64-bit x86. Maybe for compat 32-bit binaries we could keep it off, 
> > but always do it for 64-bit binaries.
> 
> So what do you think is proper behavior in situation when 
> CONFIG_COMPAT_BRK=N on 64bit kernel, and 32bit-binary is loaded in 
> 32bit emulation?
> 
> We can either leave the brk as-is, but that is in contradiction to 
> user explictly specifying CONFIG_COMPAT_BRK=N. Is this what you 
> propose?
> 
> Or we can randomize brk start in such situation, but that is the 
> behavior we currently automatically have due to CONFIG_COMPAT_BRK=N, 
> so no change is needed.

thinking about it ... i think we should just keep this simple, and when 
COMPAT_BRK=y then we disable brk randomization globally. If !COMPAT_BRK 
then we do brk randomization globally as well. (and that is probably 
what users want the sysctl to do anyway - users wont necessarily know 
whether the app breakage they want to solve is due to 32-bit or 64-bit.)

	Ingo

  reply	other threads:[~2008-02-07 15:02 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-06 13:45 [PATCH 0/2] brk and randomization fixes Jiri Kosina
2008-02-06 13:45 ` [PATCH 1/2] brk: check the lower bound properly Jiri Kosina
2008-02-06 13:45 ` [PATCH 2/2] ASLR: add possibility for more fine-grained tweaking Jiri Kosina
2008-02-06 13:49   ` Ingo Molnar
2008-02-06 16:26     ` [PATCH] Document randomize_va_space and CONFIG_COMPAT_BRK (was Re: [PATCH 2/2] ASLR: add possibility for more fine-grained tweaking) Jiri Kosina
2008-02-06 23:10       ` Ingo Molnar
2008-02-07  9:49         ` Jiri Kosina
2008-02-07 14:30         ` Jiri Kosina
2008-02-07 15:01           ` Ingo Molnar [this message]
2008-02-07 10:23     ` [PATCH 2/2] ASLR: add possibility for more fine-grained tweaking Geert Uytterhoeven
2008-02-07 10:31       ` Ismail Dönmez
2008-02-07 10:32       ` Ingo Molnar
2008-02-07 10:43         ` Geert Uytterhoeven

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