Ensure that the request_queue is refcounted during its full
ioctl cycle. This avoids possible races against removal, given
blk_get_queue() also checks to ensure the queue is not dying.
This small race is possible if you defer removal of the request_queue
and userspace fires off an ioctl for the device in the meantime.
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Omar Sandoval <osandov@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Nicolai Stange <nstange@xxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: yu kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
---
kernel/trace/blktrace.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 15086227592f..17e144d15779 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -701,6 +701,9 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
if (!q)
return -ENXIO;
+ if (!blk_get_queue(q))
+ return -ENXIO;
+
mutex_lock(&q->blk_trace_mutex);
switch (cmd) {
@@ -729,6 +732,9 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
}
mutex_unlock(&q->blk_trace_mutex);
+
+ blk_put_queue(q);
+
return ret;
}
--
2.25.1
