linux-kernel - Re: Sanitize CPU-state when switching tasks (was sanitize CPU-state when switching from virtual-8086 mode to other task)

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Message-ID: <20140108193655.GD5098@pd.tnic>
Date:	Wed, 8 Jan 2014 20:36:55 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	halfdog <me@...fdog.net>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Ben Hutchings <ben@...adent.org.uk>
Subject: Re: Sanitize CPU-state when switching tasks (was sanitize CPU-state
 when switching from virtual-8086 mode to other task)

On Wed, Jan 08, 2014 at 09:42:40AM -0800, H. Peter Anvin wrote:
> Adding Borislav.
> 
> Boris, do you happen to know of any erratum on AMD E-350 which may be
> in play here?

Interesting. Well, nothing looks even remotely related from looking at the F14h
rev guide here:

http://developer.amd.com/wordpress/media/2012/10/47534_14h_Mod_00h-0Fh_Rev_Guide.pdf

Btw, hd (if that is your real name :-)), can you post /proc/cpuinfo? I
think I might have a E-350 here too and I could try to reproduce. Btw,
how exactly do you trigger?

You run FpuStateTaskSwitchShmemXattrHandlersOverwriteWithNullPage.c
first to modify shmem_xattr_handlers and then
ManipulatedXattrHandlerForPrivEscalation.c? You need a 32-bit kernel and
userspace, right? Anything else?

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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