blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq)
{
	unsigned long flags;
	int where = ELEVATOR_INSERT_BACK;

	if (blk_cloned_rq_check_limits(q, rq))
		return BLK_STS_IOERR;

	if (rq->rq_disk &&
	    should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
		return BLK_STS_IOERR;

	if (q->mq_ops) {
		if (blk_queue_io_stat(q))
			blk_account_io_start(rq, true);
		/*
		 * Since we have a scheduler attached on the top device,
		 * bypass a potential scheduler on the bottom device for
		 * insert.
		 */
		return blk_mq_request_issue_directly(rq);
	}

	spin_lock_irqsave(q->queue_lock, flags);
	if (unlikely(blk_queue_dying(q))) {
		spin_unlock_irqrestore(q->queue_lock, flags);
		return BLK_STS_IOERR;
	}

	/*
	 * Submitting request must be dequeued before calling this function
	 * because it will be linked to another request_queue
	 */
	BUG_ON(blk_queued_rq(rq));

	if (op_is_flush(rq->cmd_flags))
		where = ELEVATOR_INSERT_FLUSH;

	add_acct_request(q, rq, where);
	if (where == ELEVATOR_INSERT_FLUSH)
		__blk_run_queue(q);
	spin_unlock_irqrestore(q->queue_lock, flags);

	return BLK_STS_OK;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.