static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
		     loff_t pos, bool rw)
{
	struct iov_iter iter;
	struct bio_vec *bvec;
	struct request *rq = cmd->rq;
	struct bio *bio = rq->bio;
	struct file *file = lo->lo_backing_file;
	unsigned int offset;
	int segments = 0;
	int ret;

	if (rq->bio != rq->biotail) {
		struct req_iterator iter;
		struct bio_vec tmp;

		__rq_for_each_bio(bio, rq)
			segments += bio_segments(bio);
		bvec = kmalloc(sizeof(struct bio_vec) * segments, GFP_NOIO);
		if (!bvec)
			return -EIO;
		cmd->bvec = bvec;

		/*
		 * The bios of the request may be started from the middle of
		 * the 'bvec' because of bio splitting, so we can't directly
		 * copy bio->bi_iov_vec to new bvec. The rq_for_each_segment
		 * API will take care of all details for us.
		 */
		rq_for_each_segment(tmp, rq, iter) {
			*bvec = tmp;
			bvec++;
		}
		bvec = cmd->bvec;
		offset = 0;
	} else {
		/*
		 * Same here, this bio may be started from the middle of the
		 * 'bvec' because of bio splitting, so offset from the bvec
		 * must be passed to iov iterator
		 */
		offset = bio->bi_iter.bi_bvec_done;
		bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
		segments = bio_segments(bio);
	}
	atomic_set(&cmd->ref, 2);

	iov_iter_bvec(&iter, ITER_BVEC | rw, bvec,
		      segments, blk_rq_bytes(rq));
	iter.iov_offset = offset;

	cmd->iocb.ki_pos = pos;
	cmd->iocb.ki_filp = file;
	cmd->iocb.ki_complete = lo_rw_aio_complete;
	cmd->iocb.ki_flags = IOCB_DIRECT;
	if (cmd->css)
		kthread_associate_blkcg(cmd->css);

	if (rw == WRITE)
		ret = call_write_iter(file, &cmd->iocb, &iter);
	else
		ret = call_read_iter(file, &cmd->iocb, &iter);

	lo_rw_aio_do_completion(cmd);
	kthread_associate_blkcg(NULL);

	if (ret != -EIOCBQUEUED)
		cmd->iocb.ki_complete(&cmd->iocb, ret, 0);
	return 0;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.