linux-kernel - Re: [PATCH 2/2] ASLR: add possibility for more fine-grained tweaking

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Message-Id: <200802071231.47614.ismail@pardus.org.tr>
Date:	Thu, 7 Feb 2008 12:31:47 +0200
From:	Ismail Dönmez <ismail@...dus.org.tr>
To:	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Jiri Kosina <jkosina@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	Hugh Dickins <hugh@...itas.com>, Pavel Machek <pavel@....cz>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ASLR: add possibility for more fine-grained tweaking

At Thursday 07 February 2008 around 12:23:50 Geert Uytterhoeven wrote:
> On Wed, 6 Feb 2008, Ingo Molnar wrote:
> > @@ -541,6 +541,18 @@ config ELF_CORE
> >       help
> >         Enable support for generating core dumps. Disabling saves about
> > 4k. 
> > +config COMPAT_BRK
> > +     bool "Disable heap randomization"
> > +     default y
> > +     help
> > +       Randomizing heap placement makes heap exploits harder, but it
> > +       also breaks ancient binaries (including anything libc5 based).
> > +       This option changes the bootup default to heap randomization
> > +       disabled, and can be overriden runtime by setting
> > +       /proc/sys/kernel/randomize_va_space to 2.
> > +
> > +       On non-ancient distros (post-2000 ones) Y is usually a safe
> > choice.
>
> Somehow my belly feeling tells me something is wrong with this
> description...
>
> Ah, a negative option (Y -> disable).  So Y is always safe.
>
> `non-ancient distros' really means `recent distros', and if you have one,
> then _N_ should be a safe choice, too?

This indeed looks wrong. The default should be N and the text should say "On 
recent distros (post-2000 ones) N is usually a safe choice".

Regards,
ismail

-- 
Never learn by your mistakes, if you do you may never dare to try again.
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