Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753780Ab0KITTO (ORCPT ); Tue, 9 Nov 2010 14:19:14 -0500 Received: from smtp.outflux.net ([198.145.64.163]:59707 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753431Ab0KITTM (ORCPT ); Tue, 9 Nov 2010 14:19:12 -0500 Date: Tue, 9 Nov 2010 11:19:08 -0800 From: Kees Cook To: Pekka Enberg Cc: x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] x86: call verify_cpu during 32bit CPU startup Message-ID: <20101109191908.GO5876@outflux.net> References: <20101109181157.GE5876@outflux.net> <20101109181525.GH5876@outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Canonical X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 928 Lines: 22 On Tue, Nov 09, 2010 at 09:09:18PM +0200, Pekka Enberg wrote: > On Tue, Nov 9, 2010 at 8:15 PM, Kees Cook wrote: > > The XD_DISABLE-clearing side-effect needs to happen on 32bit CPU > > start-up as well. > > > > Signed-off-by: Kees Cook > > The patch description here is pretty damn terse. Why do we need the > clearing for? Does not clearing XD_DISABLE cause some problem? The clearing needs to happen for both 32bit and 64bit, but the 32bit init routines were not calling verify_cpu() yet. This adds that path to gain the side-effect. (See patch 0 for why clearing XD_DISABLE is important.) -- Kees Cook Ubuntu Security Team -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/