From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753781AbaEHJol (ORCPT ); Thu, 8 May 2014 05:44:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44682 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753609AbaEHJoj (ORCPT ); Thu, 8 May 2014 05:44:39 -0400 Date: Thu, 8 May 2014 17:46:06 +0800 From: Dave Young To: Kees Cook Cc: "H. Peter Anvin" , LKML Subject: Re: kaslr should avoid setup_data region Message-ID: <20140508094606.GE3320@darkstar.nay.redhat.com> References: <20140424023544.GA2180@darkstar.nay.redhat.com> <20140424025016.GB2180@darkstar.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/24/14 at 03:50pm, Kees Cook wrote: > Ah, it sounds like boot_params.hdr.setup_data contains a series of > e820-like entries chained together as a linked list? Which loaders > currently populate that? Looks like EFI? Seems like > arch/x86/boot/compressed/eboot.c works on setup_data at least. > > I won't be in a position to test EFI booting for a while. If someone > else took this, that would make it get fixed much faster. > > Do you have examples where this is actually causing failures? > > -Kees > > On Wed, Apr 23, 2014 at 7:50 PM, Dave Young wrote: > > On 04/23/14 at 07:43pm, Kees Cook wrote: > >> On Wed, Apr 23, 2014 at 7:35 PM, Dave Young wrote: > >> > Hello Kees > >> > > >> > I'm worrying that setup_data regions could be overwitten by randomize > >> > kernel base. Would you like to fix it in kaslr code? > >> > > >> > One problem is there could be a lot of setup_data regions but current > >> > mem_avoid is an fixed array. > >> > >> Sure, can you give me some examples? Seems like it shouldn't be too > >> hard to have the mem_avoid logic walk additional areas. > > > > Great, To walk through the list just like the function parse_setup_data in > > arch/x86/kernel/setup.c One problem for me is that I am not sure how to read the setup_data memory and iterate it, I think early_ioremap is not available that early. BTW the setup_data region could be above 4G. Appreciate for any hints. Thanks Dave