linux-kernel - Re: [RFC][PATCH] Randomize kernel base address on boot

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Message-ID: <26081.1306440965@turing-police.cc.vt.edu>
Date:	Thu, 26 May 2011 16:16:05 -0400
From:	Valdis.Kletnieks@...edu
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Dan Rosenberg <drosenberg@...curity.com>,
	Tony Luck <tony.luck@...il.com>, linux-kernel@...r.kernel.org,
	davej@...hat.com, kees.cook@...onical.com, davem@...emloft.net,
	eranian@...gle.com, torvalds@...ux-foundation.org,
	adobriyan@...il.com, penberg@...nel.org, hpa@...or.com,
	Arjan van de Ven <arjan@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, pageexec@...email.hu
Subject: Re: [RFC][PATCH] Randomize kernel base address on boot

On Thu, 26 May 2011 16:01:21 EDT, Vivek Goyal said:

> Also randomization of kernel load address at run time will probably have
> some issues with crashkernel=X@Y address syntax. So far user knew what
> address first kernel is booting from and user could speicy where to 
> reserve memory. Now it might happen that user specified some memory
> to reserve and kernel decided to occupy that space resulting in failed
> memory reservation for crash kernel.

That is however fixable - the randomizer just needs to make sure it doesn't
overlay the crashkernel= space, and the crashkernel needs to be started with a
'norandomize' parameter.  If your threat model includes attacks on the
crashkernel that randomizing will help with, you got bigger problems. ;)


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