From: Rogier Wolff <R.E.Wolff@BitWizard.nl>
To: Kees Cook <kees.cook@canonical.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [Security] [PATCH v3 0/4] x86: clear XD_DISABLED flag on Intel to regain NX
Date: Thu, 11 Nov 2010 16:15:20 +0100 [thread overview]
Message-ID: <20101111151520.GA20168@bitwizard.nl> (raw)
In-Reply-To: <20101110011039.GG5876@outflux.net>
On Tue, Nov 09, 2010 at 05:10:39PM -0800, Kees Cook wrote:
> AG29. #GP Fault is Not Generated on Writing IA32_MISC_ENABLE [34]
> When Execute Disable (XD) is Not Supported
> Problem: A #GP fault is not generated on writing to IA32_MISC_ENABLE [34]
> bit in a processor which does not support Execute Disable (XD)
> functionality.
> Implication: Writing to IA32_MISC_ENABLE [34] bit is silently ignored
> without generating a fault.
> Workaround: None identified.
> Status: For the steppings affected, see the Summary Tables of Changes.
> But this case is already handled (and doesn't matter) because my
> patch already avoids this (we only clear IA32_MISC_ENABLE, not set
> it).
Ehhh. A Virtual machine monitor may need to be notified of your
"clearing" that bit. The erratum is correctly worded as for "writing"
not "setting".
But that bug is intel's problem. Not yours.
Roger.
--
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** Delftechpark 26 2628 XH Delft, The Netherlands. KVK: 27239233 **
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prev parent reply other threads:[~2010-11-11 15:15 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-09 18:11 [Security] [PATCH v3 0/4] x86: clear XD_DISABLED flag on Intel to regain NX Kees Cook
2010-11-09 18:14 ` [PATCH 1/4] x86: rename verify_cpu_64.S to verify_cpu.S Kees Cook
2010-11-09 18:46 ` Pekka Enberg
2010-11-09 19:00 ` Kees Cook
2010-11-09 19:59 ` Pekka Enberg
2010-11-09 19:02 ` Kees Cook
2010-11-09 19:11 ` Pekka Enberg
2010-11-09 18:15 ` [PATCH 2/4] x86: clear XD_DISABLED flag on Intel to regain NX Kees Cook
2010-11-10 16:11 ` Andi Kleen
2010-11-10 16:47 ` Kees Cook
2010-11-10 17:42 ` Andi Kleen
2010-11-10 18:15 ` Kees Cook
2010-11-09 18:15 ` [PATCH 3/4] x86: call verify_cpu during 32bit CPU startup Kees Cook
2010-11-09 19:09 ` Pekka Enberg
2010-11-09 19:19 ` Kees Cook
2010-11-09 19:46 ` Pekka Enberg
2010-11-09 19:56 ` Kees Cook
2010-11-09 20:28 ` Pekka Enberg
2010-11-09 20:48 ` Kees Cook
2010-11-09 20:50 ` Pekka Enberg
2010-11-09 18:15 ` [PATCH 4/4] x86: only CPU features determine NX capabilities Kees Cook
2010-11-09 18:31 ` [Security] [PATCH v3 0/4] x86: clear XD_DISABLED flag on Intel to regain NX Alan Cox
2010-11-09 18:56 ` Kees Cook
2010-11-09 22:50 ` Alan Cox
2010-11-09 23:53 ` Kees Cook
2010-11-10 0:21 ` Alan Cox
2010-11-10 0:43 ` Kees Cook
2010-11-10 1:10 ` Kees Cook
2010-11-10 11:11 ` Alan Cox
2010-11-10 11:15 ` Ingo Molnar
2010-11-11 15:15 ` Rogier Wolff [this message]
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