From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263264AbTECGj5 (ORCPT ); Sat, 3 May 2003 02:39:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263265AbTECGj5 (ORCPT ); Sat, 3 May 2003 02:39:57 -0400 Received: from nat-pool-rdu.redhat.com ([66.187.233.200]:40644 "EHLO devserv.devel.redhat.com") by vger.kernel.org with ESMTP id S263264AbTECGj4 (ORCPT ); Sat, 3 May 2003 02:39:56 -0400 Date: Sat, 3 May 2003 02:52:21 -0400 (EDT) From: Ingo Molnar X-X-Sender: mingo@devserv.devel.redhat.com To: Carl-Daniel Hailfinger cc: linux-kernel@vger.kernel.org Subject: Re: [Announcement] "Exec Shield", new Linux security feature In-Reply-To: <3EB2E7B1.40006@gmx.net> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2 May 2003, Carl-Daniel Hailfinger wrote: > Ingo Molnar wrote: > > > > Furthermore, the kernel also remaps all PROT_EXEC mappings to the > > so-called ASCII-armor area, which on x86 is the addresses 0-16MB. These > [snipped] > > In the above layout, the highest executable address is 0x01003fff, ie. > > every executable address is in the ASCII-armor. > > If my math is correct, > 0x01000000 is 16 MB boundary > 0x01003fff is outside the ASCII-armor. the ASCII-armor, more precisely, is between addresses 0x00000000 and 0x0100ffff. Ie. 16 MB + 64K. [in the remaining 64K the \0 character is in the second byte of the address.] So the 0x01003fff address is still inside the ASCII-armor. > Another question: Last time I checked, there were some problems with > binary only drivers (to name one, NVidia graphics) and a non-executable > stack. Has this been resolved? i'm not using any binary-only drivers, so i have no idea. But as long as they use PROT_EXEC areas for code, they should be safe. Ingo