From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753327AbYJXEjr (ORCPT ); Fri, 24 Oct 2008 00:39:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751214AbYJXEjE (ORCPT ); Fri, 24 Oct 2008 00:39:04 -0400 Received: from kroah.org ([198.145.64.141]:51604 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751146AbYJXEjC (ORCPT ); Fri, 24 Oct 2008 00:39:02 -0400 Date: Thu, 23 Oct 2008 21:33:27 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org, jejb@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, David Brownell Subject: [patch 01/27] gpiolib: fix oops in gpio_get_value_cansleep() Message-ID: <20081024043327.GB30828@kroah.com> References: <20081024042023.054190751@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="gpiolib-fix-oops-in-gpio_get_value_cansleep.patch" In-Reply-To: <20081024043303.GA30828@kroah.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: David Brownell commit 978ccaa8ea5d8c7bf6b676209f2fc126eae6355b upstream We can get the following oops from gpio_get_value_cansleep() when a GPIO controller doesn't provide a get() callback: Unable to handle kernel paging request for instruction fetch Faulting instruction address: 0x00000000 Oops: Kernel access of bad area, sig: 11 [#1] [...] NIP [00000000] 0x0 LR [c0182fb0] gpio_get_value_cansleep+0x40/0x50 Call Trace: [c7b79e80] [c0183f28] gpio_value_show+0x5c/0x94 [c7b79ea0] [c01a584c] dev_attr_show+0x30/0x7c [c7b79eb0] [c00d6b48] fill_read_buffer+0x68/0xe0 [c7b79ed0] [c00d6c54] sysfs_read_file+0x94/0xbc [c7b79ef0] [c008f24c] vfs_read+0xb4/0x16c [c7b79f10] [c008f580] sys_read+0x4c/0x90 [c7b79f40] [c0013a14] ret_from_syscall+0x0/0x38 It's OK to request the value of *any* GPIO; most GPIOs are bidirectional, so configuring them as outputs just enables an output driver and doesn't disable the input logic. So the problem is that gpio_get_value_cansleep() isn't making the same sanity check that gpio_get_value() does: making sure this GPIO isn't one of the atypical "no input logic" cases. Reported-by: Anton Vorontsov Signed-off-by: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/gpio/gpiolib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1020,7 +1020,7 @@ int gpio_get_value_cansleep(unsigned gpi might_sleep_if(extra_checks); chip = gpio_to_chip(gpio); - return chip->get(chip, gpio - chip->base); + return chip->get ? chip->get(chip, gpio - chip->base) : 0; } EXPORT_SYMBOL_GPL(gpio_get_value_cansleep); --