void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
	struct request_queue *q;
	struct request *rq;
	LIST_HEAD(list);
	unsigned int depth;

	flush_plug_callbacks(plug, from_schedule);

	if (!list_empty(&plug->mq_list))
		blk_mq_flush_plug_list(plug, from_schedule);

	if (list_empty(&plug->list))
		return;

	list_splice_init(&plug->list, &list);

	list_sort(NULL, &list, plug_rq_cmp);

	q = NULL;
	depth = 0;

	while (!list_empty(&list)) {
		rq = list_entry_rq(list.next);
		list_del_init(&rq->queuelist);
		BUG_ON(!rq->q);
		if (rq->q != q) {
			/*
			 * This drops the queue lock
			 */
			if (q)
				queue_unplugged(q, depth, from_schedule);
			q = rq->q;
			depth = 0;
			spin_lock_irq(q->queue_lock);
		}

		/*
		 * Short-circuit if @q is dead
		 */
		if (unlikely(blk_queue_dying(q))) {
			__blk_end_request_all(rq, BLK_STS_IOERR);
			continue;
		}

		/*
		 * rq is already accounted, so use raw insert
		 */
		if (op_is_flush(rq->cmd_flags))
			__elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
		else
			__elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);

		depth++;
	}

	/*
	 * This drops the queue lock
	 */
	if (q)
		queue_unplugged(q, depth, from_schedule);
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.