Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758092AbZFCSup (ORCPT ); Wed, 3 Jun 2009 14:50:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755366AbZFCSrU (ORCPT ); Wed, 3 Jun 2009 14:47:20 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:53915 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755580AbZFCSrS (ORCPT ); Wed, 3 Jun 2009 14:47:18 -0400 Date: Wed, 3 Jun 2009 11:45:38 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: "Larry H." cc: Alan Cox , Christoph Lameter , linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org, pageexec@freemail.hu Subject: Re: Security fix for remapping of page 0 (was [PATCH] Change ZERO_SIZE_PTR to point at unmapped space) In-Reply-To: <20090603183939.GC18561@oblivion.subreption.com> Message-ID: References: <20090530230022.GO6535@oblivion.subreption.com> <20090531022158.GA9033@oblivion.subreption.com> <20090602203405.GC6701@oblivion.subreption.com> <20090603182949.5328d411@lxorguk.ukuu.org.uk> <20090603180037.GB18561@oblivion.subreption.com> <20090603183939.GC18561@oblivion.subreption.com> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 942 Lines: 24 On Wed, 3 Jun 2009, Larry H. wrote: > > > > The fact, the NULL pointer attack is neither easy nor common. It's > > perfectly reasonable to say "we'll allow mmap at virtual address zero". > > And how could you calibrate if this attack venue isn't easy to take > advantage of? Or not commonly abused? What empirical results led you to this > conclusion? It's not a primary attack vector. You need to have already broken local security to get there - you need to be able to execute code. That means that you've already by-passed all the main security. It's thus by definition less common than attack vectors like buffer overflows that give you that capability in the first place. Linus -- 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/