From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754068Ab1HAX0x (ORCPT ); Mon, 1 Aug 2011 19:26:53 -0400 Received: from cantor2.suse.de ([195.135.220.15]:38708 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753971Ab1HAX0i (ORCPT ); Mon, 1 Aug 2011 19:26:38 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Aug 1 16:20:55 2011 Message-Id: <20110801232055.630132100@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Mon, 01 Aug 2011 16:19:05 -0700 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, Pavel Herrmann , Russell King , Pavel Machek , Marek Vasut , Cyril Hrubis , Jean Delvare Subject: [50/70] hwmon: (max1111) Fix race condition causing NULL pointer exception In-Reply-To: <20110801232124.GA15313@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.39-stable review patch. If anyone has any objections, please let us know. ------------------ From: Pavel Herrmann commit d3f684f2820a7f42acef68bea6622d9032127fb2 upstream. spi_sync call uses its spi_message parameter to keep completion information, using a drvdata structure is not thread-safe. Use a mutex to prevent multiple access to shared driver data. Signed-off-by: Pavel Herrmann Acked-by: Russell King Acked-by: Pavel Machek Acked-by: Marek Vasut Acked-by: Cyril Hrubis Tested-by: Stanislav Brabec Signed-off-by: Jean Delvare Signed-off-by: Greg Kroah-Hartman --- drivers/hwmon/max1111.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/drivers/hwmon/max1111.c +++ b/drivers/hwmon/max1111.c @@ -40,6 +40,8 @@ struct max1111_data { struct spi_transfer xfer[2]; uint8_t *tx_buf; uint8_t *rx_buf; + struct mutex drvdata_lock; + /* protect msg, xfer and buffers from multiple access */ }; static int max1111_read(struct device *dev, int channel) @@ -48,6 +50,9 @@ static int max1111_read(struct device *d uint8_t v1, v2; int err; + /* writing to drvdata struct is not thread safe, wait on mutex */ + mutex_lock(&data->drvdata_lock); + data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) | MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 | MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR; @@ -55,12 +60,15 @@ static int max1111_read(struct device *d err = spi_sync(data->spi, &data->msg); if (err < 0) { dev_err(dev, "spi_sync failed with %d\n", err); + mutex_unlock(&data->drvdata_lock); return err; } v1 = data->rx_buf[0]; v2 = data->rx_buf[1]; + mutex_unlock(&data->drvdata_lock); + if ((v1 & 0xc0) || (v2 & 0x3f)) return -EINVAL; @@ -176,6 +184,8 @@ static int __devinit max1111_probe(struc if (err) goto err_free_data; + mutex_init(&data->drvdata_lock); + data->spi = spi; spi_set_drvdata(spi, data); @@ -213,6 +223,7 @@ static int __devexit max1111_remove(stru hwmon_device_unregister(data->hwmon_dev); sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); + mutex_destroy(&data->drvdata_lock); kfree(data->rx_buf); kfree(data->tx_buf); kfree(data);