Messages in this thread Patch in this message | | | Date | Fri, 20 Mar 2009 10:34:00 +0800 | From | Li Zefan <> | Subject | Re: [PATCH 7/7] blktrace: avoid accessing NULL bdev->bd_disk |
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> +static request_queue *blk_trace_get_queue(struct block_device *bdev) > +{
Sorry, should be "struct request_queue", I forgot to re-format the patch after I fixed this.
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From: Li Zefan <lizf@cn.fujitsu.com> Subject: [PATCH 7/7] blktrace: avoid accessing NULL bdev->bd_disk
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 <lizf@cn.fujitsu.com> --- 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..d2dd9ed 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 struct 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
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