From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424217AbcFMVZf (ORCPT ); Mon, 13 Jun 2016 17:25:35 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:47237 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423828AbcFMVZd (ORCPT ); Mon, 13 Jun 2016 17:25:33 -0400 Date: Mon, 13 Jun 2016 22:25:16 +0100 From: Russell King - ARM Linux To: Kees Cook Cc: "linux-arm-kernel@lists.infradead.org" , Ard Biesheuvel , Nicolas Pitre , Chris Brandt , Arnd Bergmann , Alexander Potapenko , Marc Zyngier , LKML Subject: Re: [PATCH] ARM: mm: fix location of _etext Message-ID: <20160613212515.GA1041@n2100.armlinux.org.uk> References: <20160608231158.GA12159@www.outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 13, 2016 at 01:23:29PM -0700, Kees Cook wrote: > On Wed, Jun 8, 2016 at 4:11 PM, Kees Cook wrote: > > The _etext position is defined to be the end of the kernel text code, > > and should not include any part of the data segments. This interferes > > with things that might check memory ranges and expect executable code > > up to _etext. > > > > Signed-off-by: Kees Cook > > Can someone give this an Ack? I'd like to land it as it is a > prerequisite to some usercopy hardening work I'm doing. We use _etext to place the end of the "kernel code" resource in /proc/iomem, and init_mm.end_code. I don't think anything makes use of init_mm.end_code, but I'm more worried about the resource. Currently, because of where _etext is placed, "kernel code" covers the read-only data and other read-only sections as well - I don't know whether we need to preserve that, but this change has a side effect of changing that. Maybe we also need a "kernel rodata" resource? -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.