From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752969AbdDJTEA (ORCPT ); Mon, 10 Apr 2017 15:04:00 -0400 Received: from mail-io0-f181.google.com ([209.85.223.181]:34969 "EHLO mail-io0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752002AbdDJTD6 (ORCPT ); Mon, 10 Apr 2017 15:03:58 -0400 MIME-Version: 1.0 In-Reply-To: References: From: Kees Cook Date: Mon, 10 Apr 2017 12:03:55 -0700 X-Google-Sender-Auth: S7611QNMv1WiyDtM7kO8JKT_Aws Message-ID: Subject: Re: KASLR causes intermittent boot failures on some systems To: Jeff Moyer Cc: Thomas Garnier , Ingo Molnar , Baoquan He , Dan Williams , LKML , linux-nvdimm@ml01.01.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 10, 2017 at 11:22 AM, Jeff Moyer wrote: > Kees Cook writes: > >> On Mon, Apr 10, 2017 at 8:49 AM, Jeff Moyer wrote: >>> Kees Cook writes: >>> >>>> On Fri, Apr 7, 2017 at 7:41 AM, Jeff Moyer wrote: >>>>> Hi, >>>>> >>>>> commit 021182e52fe01 ("x86/mm: Enable KASLR for physical mapping memory >>>>> regions") causes some of my systems with persistent memory (whether real >>>>> or emulated) to fail to boot with a couple of different crash >>>>> signatures. The first signature is a NMI watchdog lockup of all but 1 >>>>> cpu, which causes much difficulty in extracting useful information from >>>>> the console. The second variant is an invalid paging request, listed >>>>> below. >>>> >>>> Just to rule out some of the stuff in the boot path, does booting with >>>> "nokaslr" solve this? (i.e. I want to figure out if this is from some >>>> of the rearrangements done that are exposed under that commit, or if >>>> it is genuinely the randomization that is killing the systems...) >>> >>> Adding "nokaslr" to the boot line does indeed make the problem go away. >> >> Are you booting with a memmap= flag? > > From my first email: > > [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-4.11.0-rc5+ > root=/dev/mapper/rhel_intel--lizardhead--04-root ro memmap=192G!1024G > crashkernel=auto rd.lvm.lv=rhel_intel-lizardhead-04/root > rd.lvm.lv=rhel_intel-lizardhead-04/swap console=ttyS0,115200n81 > LANG=en_US.UTF-8 > > Did you not receive the attachments? I see it now, thanks! The memmap parsing was added in -rc1 (f28442497b5ca), so I'd expect that to be handled. Hmmm. -Kees -- Kees Cook Pixel Security