Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162863Ab3DEWJI (ORCPT ); Fri, 5 Apr 2013 18:09:08 -0400 Received: from terminus.zytor.com ([198.137.202.10]:40114 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162790Ab3DEWJG (ORCPT ); Fri, 5 Apr 2013 18:09:06 -0400 Message-ID: <515F4B60.60302@zytor.com> Date: Fri, 05 Apr 2013 15:08:32 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: Julien Tinnes CC: Ingo Molnar , Kees Cook , LKML , "kernel-hardening@lists.openwall.com" , Thomas Gleixner , Ingo Molnar , "x86@kernel.org" , Jarkko Sakkinen , Matthew Garrett , Matt Fleming , Eric Northup , Dan Rosenberg , Will Drewry Subject: Re: [PATCH 3/3] x86: kernel base offset ASLR References: <1365106055-22939-1-git-send-email-keescook@chromium.org> <1365106055-22939-4-git-send-email-keescook@chromium.org> <20130405071144.GB26889@gmail.com> In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 772 Lines: 22 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. -hpa -- 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/