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authorLi Zefan <lizf@cn.fujitsu.com>2009-03-20 10:34:00 +0800
committerIngo Molnar <mingo@elte.hu>2009-03-21 16:17:24 +0100
commitb125130b22d67f249beba10b71a254558b5279d0 (patch)
treef42f4f732a2d7920009f34d798d1803def38ea44
parentcd649b8bb830d65c57c3c8b98d57b5402256d8bd (diff)
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> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <49C30098.6080107@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/trace/blktrace.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index dfee6f915179..108f4f7715a5 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;