Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932613AbaLAWp2 (ORCPT ); Mon, 1 Dec 2014 17:45:28 -0500 Received: from mail-vc0-f179.google.com ([209.85.220.179]:56215 "EHLO mail-vc0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754026AbaLAWp1 (ORCPT ); Mon, 1 Dec 2014 17:45:27 -0500 MIME-Version: 1.0 In-Reply-To: References: Date: Mon, 1 Dec 2014 23:45:26 +0100 Message-ID: Subject: Re: PROBLEM: [Launchpad #1396889] [Lenovo ThinkPad T400] kexec reboot fails From: MegaBrutal To: Linux kernel Cc: Kees Cook Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2014-12-01 7:32 GMT+01:00 MegaBrutal : > [X.] Other notes, patches, fixes, workarounds: > Downstream report (Ubuntu Launchpad): > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1396889 > > With kernel bisection, I've found, the first bad commit is > 8ab3820fd5b2896d66da7bb2a906bc382e63e7bc x86, kaslr: Return location > from decompress_kernel > which introduces KASLR. > http://lkml.kernel.org/r/1381450698-28710-3-git-send-email-keescook@chromium.org > > The problem only presents itself when CONFIG_RANDOMIZE_BASE=y. > > For workaround, there is a "nokaslr" kernel parameter to disable the > feature, even if the kernel was compiled with CONFIG_RANDOMIZE_BASE. Need to add: as I tested today, unfortunately the "nokaslr" kernel option doesn't work around the bug. If a kernel was compiled with CONFIG_RANDOMIZE_BASE, it won't properly kexec on my ThinkPad T400, even if the "nokaslr" kernel option is provided! This could actually help to find the bug, as whatever bad happens must happen before the kernel checks for the presence of the "nokaslr" kernel parameter. -- 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/