Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752801Ab3JBFcF (ORCPT ); Wed, 2 Oct 2013 01:32:05 -0400 Received: from terminus.zytor.com ([198.137.202.10]:58265 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751766Ab3JBFcB (ORCPT ); Wed, 2 Oct 2013 01:32:01 -0400 Message-ID: <524BAF92.1090705@zytor.com> Date: Tue, 01 Oct 2013 22:30:58 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Ingo Molnar CC: Kees Cook , linux-kernel@vger.kernel.org, x86@kernel.org, kernel-hardening@lists.openwall.com, adurbin@google.com, Eric Northup , jln@google.com, wad@google.com, Mathias Krause , Zhang Yanfei , Linus Torvalds , Andrew Morton , Arnaldo Carvalho de Melo , Peter Zijlstra , Thomas Gleixner Subject: Re: [PATCH v6 0/7] Kernel base address randomization References: <1380656245-29975-1-git-send-email-keescook@chromium.org> <20131002050714.GA27982@gmail.com> <20131002052531.GA31122@gmail.com> In-Reply-To: <20131002052531.GA31122@gmail.com> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1088 Lines: 28 On 10/01/2013 10:25 PM, Ingo Molnar wrote: > > I mean, for example in an oops message we print data in words: the RIP, > other registers and stack contents. If any of these values lies within the > randomization range then we could de-randomize it. > > So instead of exposing randomized values, we could expose de-randomized > values. > > ( This isn't fool-proof: if some data value happens to lie within the > random range spuriously then we'll incorrectly transform it. In the > context of oops messages this should not be a big practical problem > though. ) > I don't agree that this isn't a big practical problem. I often find it necessary to pick out "things that look like pointers". Overall, derandomization would make it possible to get really confused when you have things like half a pointer overwritten. -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/