Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935586AbdCXJnM (ORCPT ); Fri, 24 Mar 2017 05:43:12 -0400 Received: from mail-io0-f182.google.com ([209.85.223.182]:33854 "EHLO mail-io0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965056AbdCXJmr (ORCPT ); Fri, 24 Mar 2017 05:42:47 -0400 MIME-Version: 1.0 In-Reply-To: <20170324094034.2afxgg43wlezdka5@pd.tnic> References: <1490331592-31860-1-git-send-email-bhe@redhat.com> <20170324080833.GA15200@gmail.com> <20170324083451.GC30442@x1> <20170324084609.GA6807@dhcp-128-65.nay.redhat.com> <20170324092433.GA3237@gmail.com> <20170324094034.2afxgg43wlezdka5@pd.tnic> From: Ard Biesheuvel Date: Fri, 24 Mar 2017 09:42:40 +0000 Message-ID: Subject: Re: [PATCH v2] x86/mm/KASLR: EFI region is mistakenly included into KASLR VA space for randomization To: Borislav Petkov Cc: Ingo Molnar , Dave Young , Baoquan He , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "x86@kernel.org" , "linux-efi@vger.kernel.org" , Thomas Garnier , Kees Cook , Andrew Morton , Masahiro Yamada , Bhupesh Sharma Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 668 Lines: 14 On 24 March 2017 at 09:40, Borislav Petkov wrote: > On Fri, Mar 24, 2017 at 09:37:36AM +0000, Ard Biesheuvel wrote: >> No. It is the firmware's EFI code, and the virtual translation applied >> by the OS is made known to the firmware by means of a call into the >> runtime service SetVirtualAddressMap(). > > We can still randomize within those 64G before calling > SetVirtualAddressMap(). The question is, do we want to or need to, even? > That is a different matter. If the regions are only mapped while runtime services invocations are in progress (as we do on ARM), I am not sure if it matters that much, given how rarely that occurs in normal use.