From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S940542AbcKNDRR (ORCPT ); Sun, 13 Nov 2016 22:17:17 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45271 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754005AbcKNCFl (ORCPT ); Sun, 13 Nov 2016 21:05:41 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jiri Kosina" , "Jiri Kosina" , "Pavel Machek" , "Rafael J. Wysocki" , "Thomas Garnier" , "Rafael J. Wysocki" Date: Mon, 14 Nov 2016 00:14:20 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 180/346] PM / hibernate: Restore processor state before using per-CPU variables In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.39-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Garnier commit 62822e2ec4ad091ba31f823f577ef80db52e3c2c upstream. Restore the processor state before calling any other functions to ensure per-CPU variables can be used with KASLR memory randomization. Tracing functions use per-CPU variables (GS based on x86) and one was called just before restoring the processor state fully. It resulted in a double fault when both the tracing & the exception handler functions tried to use a per-CPU variable. Fixes: bb3632c6101b (PM / sleep: trace events for suspend/resume) Reported-and-tested-by: Borislav Petkov Reported-by: Jiri Kosina Tested-by: Rafael J. Wysocki Tested-by: Jiri Kosina Signed-off-by: Thomas Garnier Acked-by: Pavel Machek Signed-off-by: Rafael J. Wysocki Signed-off-by: Ben Hutchings --- kernel/power/hibernate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -301,12 +301,12 @@ static int create_image(int platform_mod save_processor_state(); trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true); error = swsusp_arch_suspend(); + /* Restore control flow magically appears here */ + restore_processor_state(); trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false); if (error) printk(KERN_ERR "PM: Error %d creating hibernation image\n", error); - /* Restore control flow magically appears here */ - restore_processor_state(); if (!in_suspend) events_check_enabled = false;