From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932114Ab2ASCTs (ORCPT ); Wed, 18 Jan 2012 21:19:48 -0500 Received: from terminus.zytor.com ([198.137.202.10]:34002 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755770Ab2ASCTq (ORCPT ); Wed, 18 Jan 2012 21:19:46 -0500 Message-ID: <4F177CF7.9070207@zytor.com> Date: Wed, 18 Jan 2012 18:16:23 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 MIME-Version: 1.0 To: Indan Zupancic CC: Linus Torvalds , Andi Kleen , Jamie Lokier , Andrew Lutomirski , Oleg Nesterov , Will Drewry , linux-kernel@vger.kernel.org, keescook@chromium.org, john.johansen@canonical.com, serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com, djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi, viro@zeniv.linux.org.uk, mingo@elte.hu, akpm@linux-foundation.org, khilman@ti.com, borislav.petkov@amd.com, amwang@redhat.com, ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de, dhowells@redhat.com, daniel.lezcano@free.fr, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, olofj@chromium.org, mhalcrow@google.com, dlaor@redhat.com, Roland McGrath Subject: Re: Compat 32-bit syscall entry from 64-bit task!? References: <20120116183730.GB21112@redhat.com> <49017bd7edab7010cd9ac767e39d99e4.squirrel@webmail.greenhost.nl> <20120118015013.GR11715@one.firstfloor.org> <20120118020453.GL7180@jl-vm1.vm.bytemark.co.uk> <20120118022217.GS11715@one.firstfloor.org> <4F1731C1.4050007@zytor.com> <4F1733DF.7040905@zytor.com> In-Reply-To: X-Enigmail-Version: 1.3.3 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 On 01/18/2012 05:45 PM, Indan Zupancic wrote: > > For security reasons it should be impossible for userspace to set those bits > themselves, otherwise the tracer can be easily fooled on an old kernel. That > seems to be the case for the higher bits of eflags, so eflags would work. And > the current code checks cs, also checking eflags would be very easy to add. > I think this goes without saying, and isn't an issue for the options currently on the table (including regset). -phpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.