memstick: ms_block: destroy io_queue workqueue on removal

In the Linux kernel, the following vulnerability has been resolved: memstick: ms_block: destroy io_queue workqueue on removal msb_init_disk() creates the per-card ordered workqueue msb->io_queue with alloc_ordered_workqueue(). It is torn down with destroy_workqueue() only on the init error path; msb_remove() never destroys it. msb_stop() merely flushes the queue, and neither msb_data_clear() nor put_disk() free it. As a result every card insert/remove cycle leaks the workqueue and its kworker, exhausting kernel memory over repeated cycles. Destroy the workqueue in msb_remove() after the disk has been removed and the queue drained.

Where it's fixed