From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 880965F0001 for ; Wed, 3 Jun 2009 14:51:33 -0400 (EDT) Date: Wed, 3 Jun 2009 11:50:16 -0700 (PDT) From: Linus Torvalds Subject: Re: Security fix for remapping of page 0 (was [PATCH] Change ZERO_SIZE_PTR to point at unmapped space) In-Reply-To: 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> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: "Larry H." Cc: Alan Cox , Christoph Lameter , linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org, pageexec@freemail.hu List-ID: On Wed, 3 Jun 2009, Linus Torvalds wrote: > > 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. Btw, you obviously need to then _also_ pair it with some as-yet-unknown case of kernel bug to get to that NULL pointer (or zero-sized-alloc pointer) problem. You _also_ seem to be totally ignoring the fact that we already _do_ protect against NULL pointers by default. So I really don't see why you're making a big deal of this. It's as if you were talking about us not randomizing the address space - sure, you can turn it off, but so what? We do it by default. So it boils down to: - NULL pointers already cannot be in mmap memory (unless a distro has done something wrong - outside of the kernel) - What's your beef? Let it go, man. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org