From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1955401AbdDYXzk (ORCPT ); Tue, 25 Apr 2017 19:55:40 -0400 Received: from mail-pg0-f51.google.com ([74.125.83.51]:33212 "EHLO mail-pg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1955386AbdDYXza (ORCPT ); Tue, 25 Apr 2017 19:55:30 -0400 Date: Tue, 25 Apr 2017 16:55:26 -0700 From: Adrian Salido To: linux-kernel@vger.kernel.org Cc: gregkh@linuxfoundation.org Subject: [PATCH] driver core: platform: fix race condition with driver_override Message-ID: <20170425235526.GA165155@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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 The driver_override implementation is susceptible to race condition when different threads are reading vs storing a different driver override. Add locking to avoid race condition. Fixes: 3d713e0e382e ("driver core: platform: add device binding path 'driver_override'") Cc: stable@vger.kernel.org Signed-off-by: Adrian Salido --- drivers/base/platform.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/base/platform.c b/drivers/base/platform.c index c2456839214a..493e03fa0e07 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -866,7 +866,7 @@ static ssize_t driver_override_store(struct device *dev, const char *buf, size_t count) { struct platform_device *pdev = to_platform_device(dev); - char *driver_override, *old = pdev->driver_override, *cp; + char *driver_override, *old, *cp; if (count > PATH_MAX) return -EINVAL; @@ -879,12 +879,15 @@ static ssize_t driver_override_store(struct device *dev, if (cp) *cp = '\0'; + device_lock(dev); + old = pdev->driver_override; if (strlen(driver_override)) { pdev->driver_override = driver_override; } else { kfree(driver_override); pdev->driver_override = NULL; } + device_unlock(dev); kfree(old); @@ -895,8 +898,12 @@ static ssize_t driver_override_show(struct device *dev, struct device_attribute *attr, char *buf) { struct platform_device *pdev = to_platform_device(dev); + ssize_t len; - return sprintf(buf, "%s\n", pdev->driver_override); + device_lock(dev); + len = sprintf(buf, "%s\n", pdev->driver_override); + device_unlock(dev); + return len; } static DEVICE_ATTR_RW(driver_override); -- 2.13.0.rc0.306.g87b477812d-goog