UBI: avoid workqueue format string leak

When building the name for the workqueue thread, make sure a format
string cannot leak in from the disk name.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

drivers/mtd/ubi/block.c

@@ -431,7 +431,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	 * Create one workqueue per volume (per registered block device).
 	 * Rembember workqueues are cheap, they're not threads.
 	 */
-	dev->wq = alloc_workqueue(gd->disk_name, 0, 0);
+	dev->wq = alloc_workqueue("%s", 0, 0, gd->disk_name);
 	if (!dev->wq)
 		goto out_free_queue;
 	INIT_WORK(&dev->work, ubiblock_do_work);