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Date: Fri, 5 Apr 2013 15:13:37 -0700
From: Julien Tinnes <>
To: "H. Peter Anvin" <>
Cc: Ingo Molnar <>, Kees Cook <>, 
	LKML <>, 
	"" <>, Thomas Gleixner <>, 
	Ingo Molnar <>, "" <>, 
	Jarkko Sakkinen <>, Matthew Garrett <>, 
	Matt Fleming <>, Eric Northup <>, 
	Dan Rosenberg <>, Will Drewry <>
Subject: Re: [PATCH 3/3] x86: kernel base offset ASLR

On Fri, Apr 5, 2013 at 3:08 PM, H. Peter Anvin <> wrote:
> On 04/05/2013 03:06 PM, Julien Tinnes wrote:
>> Speaking of IDT, and to capture some off-thread discussion here, we
>> should remember that the "SGDT" and "SIDT" instructions aren't
>> privileged on x86, so user-land can leak these out without any way for
>> the kernel to intercept that.
>> Adding their own random offsets to these two tables would be very
>> useful. This could be done in a later patchset of course.
> Yes, if the GDT or IDT position is at all correlated to the kernel
> position this is pointless.

Let's say it's less useful :) Remote attacks and from-inside-a-VM
attack would still be mitigated.


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