Date: Mon, 13 Oct 2008 21:27:29 +0200 (CEST)
From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
To: Scott Wood <scottwood@freescale.com>
cc: =?iso-8859-1?Q?Rog=E9rio?= Brito <rbrito@ime.usp.br>,
       linuxppc-dev@ozlabs.org, akpm@linux-foundation.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc: enable heap randomization for linkstations
In-Reply-To: <20081013184443.GA20612@ld0162-tx32.am.freescale.net>
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On Mon, 13 Oct 2008, Scott Wood wrote:

> On Mon, Oct 13, 2008 at 08:05:09PM +0200, Guennadi Liakhovetski wrote:
> > On Mon, 13 Oct 2008, Rog?rio Brito wrote:
> > 
> > > The current defconfig for Linkstation/Kuroboxes has the "Disable Heap
> > > Randomization" option enabled.
> > > 
> > > Since some of these machines are facing the internet, it helps to have
> > > heap randomization enabled. This patch enables it.
> > 
> > Same as the previous patch - this is one of options, that users select 
> > according to their needs. If any specific distribution enables this option 
> > by default in their kernels, they can do this too, don't think this is 
> > critical enough to patch the defconfig.
> 
> Just because users/distros can change it doesn't mean it's pointless to
> discuss what default is sane, and make changes if the current default
> isn't.
> 
> For security-related options it's usually best to default to the more
> secure state, especially since the option description talks about it
> being needed mainly for libc5 compatibility -- did libc5 ever even exist
> for powerpc?  

In a 2.6.27-rc5-ish snapshot I counted 68 enabled and 11 disabled 
CONFIG_COMPAT_BRK under arch/powerpc/configs/. Ok, enabling it for all 
would be a bit rude, and one has to start somewhere...

> The only reason it was turned on in the first place was likely the
> "default y", which in turn is there to avoid breaking old x86 distros.

Then maybe it would be better to make default y only for some platforms?

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
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