Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761022AbZCTBtq (ORCPT ); Thu, 19 Mar 2009 21:49:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761107AbZCTBtb (ORCPT ); Thu, 19 Mar 2009 21:49:31 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:55917 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1761141AbZCTBta (ORCPT ); Thu, 19 Mar 2009 21:49:30 -0400 Message-ID: <49C2F63C.2090107@cn.fujitsu.com> Date: Fri, 20 Mar 2009 09:49:48 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Ingo Molnar CC: Jens Axboe , Arnaldo Carvalho de Melo , Steven Rostedt , Frederic Weisbecker , LKML Subject: [PATCH 7/7] blktrace: avoid accessing NULL bdev->bd_disk References: <49C2F599.3060306@cn.fujitsu.com> In-Reply-To: <49C2F599.3060306@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1632 Lines: 58 bdev->bd_disk can be NULL, if the block device is not opened. Try this against an unmounted partition, and you'll see NULL dereference: # echo 1 > /sys/block/sda/sda5/enable Signed-off-by: Li Zefan --- kernel/trace/blktrace.c | 13 +++++++++++-- 1 files changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 46e0cfe..37095d9 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -1362,6 +1362,14 @@ static int blk_str2act_mask(const char *str) return mask; } +static request_queue *blk_trace_get_queue(struct block_device *bdev) +{ + if (bdev->bd_disk == NULL) + return NULL; + + return bdev_get_queue(bdev); +} + static ssize_t sysfs_blk_trace_attr_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -1376,9 +1384,10 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev, if (bdev == NULL) goto out_unlock_kernel; - q = bdev_get_queue(bdev); + q = blk_trace_get_queue(bdev); if (q == NULL) goto out_bdput; + mutex_lock(&bdev->bd_mutex); if (attr == &dev_attr_enable) { @@ -1435,7 +1444,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev, if (bdev == NULL) goto out_unlock_kernel; - q = bdev_get_queue(bdev); + q = blk_trace_get_queue(bdev); if (q == NULL) goto out_bdput; -- 1.5.4.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/