From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752381AbdIIWos (ORCPT ); Sat, 9 Sep 2017 18:44:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41465 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751861AbdIIWYn (ORCPT ); Sat, 9 Sep 2017 18:24:43 -0400 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, "Mauro Carvalho Chehab" , "kbuild test robot" , "Sean Young" Date: Sat, 09 Sep 2017 22:47:39 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 059/106] [media] rc-core: race condition during ir_raw_event_register() 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 3.2.93-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Sean Young commit 963761a0b2e85663ee4a5630f72930885a06598a upstream. A rc device can call ir_raw_event_handle() after rc_allocate_device(), but before rc_register_device() has completed. This is racey because rcdev->raw is set before rcdev->raw->thread has a valid value. Reported-by: kbuild test robot Signed-off-by: Sean Young Signed-off-by: Mauro Carvalho Chehab [bwh: Backported to 3.2: adjust filename, context, indentation] Signed-off-by: Ben Hutchings --- drivers/media/rc/ir-raw.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/drivers/media/rc/ir-raw.c +++ b/drivers/media/rc/ir-raw.c @@ -225,7 +225,7 @@ void ir_raw_event_handle(struct rc_dev * { unsigned long flags; - if (!dev->raw) + if (!dev->raw || !dev->raw->thread) return; spin_lock_irqsave(&dev->raw->lock, flags); @@ -252,6 +252,7 @@ int ir_raw_event_register(struct rc_dev { int rc; struct ir_raw_handler *handler; + struct task_struct *thread; if (!dev) return -EINVAL; @@ -269,14 +270,16 @@ int ir_raw_event_register(struct rc_dev goto out; spin_lock_init(&dev->raw->lock); - dev->raw->thread = kthread_run(ir_raw_event_thread, dev->raw, - "rc%ld", dev->devno); + thread = kthread_run(ir_raw_event_thread, dev->raw, "rc%ld", + dev->devno); - if (IS_ERR(dev->raw->thread)) { - rc = PTR_ERR(dev->raw->thread); + if (IS_ERR(thread)) { + rc = PTR_ERR(thread); goto out; } + dev->raw->thread = thread; + mutex_lock(&ir_raw_handler_lock); list_add_tail(&dev->raw->list, &ir_raw_client_list); list_for_each_entry(handler, &ir_raw_handler_list, list)