block: ublk: extending queue_size to fix overflow

When validating drafted SPDK ublk target, in a case that
assigning large queue depth to multiqueue ublk device,
ublk target would run into a weird incorrect state. During
rounds of review and debug, An overflow bug was found
in ublk driver.

In ublk_cmd.h, UBLK_MAX_QUEUE_DEPTH is 4096 which means
each ublk queue depth can be set as large as 4096. But
when setting qd for a ublk device,
sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io)
will be larger than 65535 if qd is larger than 2728.
Then queue_size is overflowed, and ublk_get_queue()
references a wrong pointer position. The wrong content of
ublk_queue elements will lead to out-of-bounds memory
access.

Extend queue_size in ublk_device as "unsigned int".
Signed-off-by: Liu Xiaodong <xiaodong.liu@intel.com>
Fixes: 71f28f31 ("ublk_drv: add io_uring based userspace block driver")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230131070552.115067-1-xiaodong.liu@intel.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/ublk_drv.c

@@ -137,7 +137,7 @@ struct ublk_device {
 
 	char	*__queues;
 
-	unsigned short  queue_size;
+	unsigned int	queue_size;
 	struct ublksrv_ctrl_dev_info	dev_info;
 
 	struct blk_mq_tag_set	tag_set;