Message-ID: <4AF99F0C.2050806@zytor.com>
Date: Tue, 10 Nov 2009 09:12:44 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Kees Cook <kees.cook@canonical.com>
CC: Arjan van de Ven <arjan@infradead.org>,
       Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
       x86@kernel.org, Pekka Enberg <penberg@cs.helsinki.fi>,
       Jan Beulich <jbeulich@novell.com>, Vegard Nossum <vegardno@ifi.uio.no>,
       Yinghai Lu <yinghai@kernel.org>,
       Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] [x86] detect and report lack of NX protections
References: <4ADD1E03.4070200@zytor.com> <20091020045513.GU5394@outflux.net> <20091109221015.GB5129@outflux.net> <4AF8A2C0.5080700@zytor.com> <20091110154956.GF5129@outflux.net> <4AF9991B.20400@zytor.com> <20091110165738.GH5129@outflux.net>
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On 11/10/2009 08:57 AM, Kees Cook wrote:
> 
> 64-bit does not set nx_enabled to "1" by default anywhere.  And setting
> the default to 1 in check_efer() seemed out of place to me.
> 

If it doesn't set nx_enabled anywhere, you'll end up with the message

+	printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
+	       "missing in CPU or disabled in BIOS!\n");

which seems obviously wrong... no?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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