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 B1CA65F0019 for ; Wed, 3 Jun 2009 13:36:26 -0400 (EDT) Date: Wed, 3 Jun 2009 10:35:10 -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: <20090603182949.5328d411@lxorguk.ukuu.org.uk> Message-ID: References: <20090530192829.GK6535@oblivion.subreption.com> <20090530230022.GO6535@oblivion.subreption.com> <20090531022158.GA9033@oblivion.subreption.com> <20090602203405.GC6701@oblivion.subreption.com> <20090603182949.5328d411@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Alan Cox Cc: Christoph Lameter , "Larry H." , linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org, pageexec@freemail.hu List-ID: On Wed, 3 Jun 2009, Alan Cox wrote: > > One way you could approach this would be to write a security module for > non SELINUX users - one that did one thing alone - decide whether the app > being run was permitted to map the low 64K perhaps by checking the > security label on the file. Unnecessary. I really think that 99% of all people are perfectly fine with just the "mmap_min_addr" rule, and no more. The rest could just use SElinux or set it to zero. It's not like allowing mmap's at NULL is a huge problem. Sure, it allows a certain kind of attack vector, but it's by no means an easy or common one - you need to already have gotten fairly good local access to take advantage of it. 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