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: 71f28f3136af ("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.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index e546932046309a66f63e2fcaf771e9d41c20ffc3..6368b56eacf11a6ac67a089c14b1435ad830b39d 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/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;