From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936588AbZLQEdW (ORCPT ); Wed, 16 Dec 2009 23:33:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S935621AbZLQEEb (ORCPT ); Wed, 16 Dec 2009 23:04:31 -0500 Received: from kroah.org ([198.145.64.141]:55560 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935512AbZLQEEZ (ORCPT ); Wed, 16 Dec 2009 23:04:25 -0500 X-Mailbox-Line: From gregkh@mini.kroah.org Wed Dec 16 19:56:51 2009 Message-Id: <20091217035650.926077960@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Wed, 16 Dec 2009 19:55:59 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Alan Stern , Oliver Neukum Subject: [062/151] Driver core: fix race in dev_driver_string In-Reply-To: <20091217040208.GA26571@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: Alan Stern commit 3589972e51fac1e02d0aaa576fa47f568cb94d40 upstream. This patch (as1310) works around a race in dev_driver_string(). If the device is unbound while the function is running, dev->driver might become NULL after we test it and before we dereference it. Signed-off-by: Alan Stern Cc: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -56,7 +56,14 @@ static inline int device_is_not_partitio */ const char *dev_driver_string(const struct device *dev) { - return dev->driver ? dev->driver->name : + struct device_driver *drv; + + /* dev->driver can change to NULL underneath us because of unbinding, + * so be careful about accessing it. dev->bus and dev->class should + * never change once they are set, so they don't need special care. + */ + drv = ACCESS_ONCE(dev->driver); + return drv ? drv->name : (dev->bus ? dev->bus->name : (dev->class ? dev->class->name : "")); }