Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751443AbaLFFBw (ORCPT ); Sat, 6 Dec 2014 00:01:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38523 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750746AbaLFFBv (ORCPT ); Sat, 6 Dec 2014 00:01:51 -0500 Date: Sat, 6 Dec 2014 13:01:40 +0800 From: Baoquan He To: MegaBrutal Cc: Kees Cook , Linux kernel , "x86@kernel.org" , "H. Peter Anvin" Subject: Re: PROBLEM: [Launchpad #1396889] [Lenovo ThinkPad T400] kexec reboot fails Message-ID: <20141206050140.GA2458@dhcp-17-102.nay.redhat.com> References: 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 12/06/14 at 04:10am, MegaBrutal wrote: > 2014-12-01 23:59 GMT+01:00 Kees Cook : > > > > I suspect you're encountering a subset of the same problems as > > described in this thread: > > https://lkml.org/lkml/2014/9/30/90 > > > > If you can test those patches, that may help demonstrate their utility. > > > > Thanks! > > Bang ji le! It works with the patch you linked, xiexie! > I suggest it to be merged into mainline. > > Anyway, is there a way to get sure that KASLR actually works now? > (I.e. how do I know if the kernel is really loaded to a random > address?) I usually check the elf header of /proc/kcore which represents the physical memory of the system and is stored in the ELF core file format. Without kaslr, the kernel text mapping should be in virtual addr 0xffffffff81000000. With kaslr enabled, the addr would be anywhere between 0xffffffff80000000 and 0xffffffffc0000000. > Do you have any idea what might be different with my ThinkPad T400 > that it is the only one of my machines affected? That's weird. I suggest you check the config file for that running kernel in your ThinkPad T400. If you have below config, that means your kernel support kaslr and enable it by default, unless you specify nokaslr in cmdline to disalbe it. CONFIG_RANDOMIZE_BASE=y CONFIG_RANDOMIZE_BASE_MAX_OFFSET=0x40000000 Different kind of machines should not affect this. Thanks Baoquan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/