static int hns_nic_tx_poll_one(struct hns_nic_ring_data *ring_data,
			       int budget, void *v)
{
	struct hnae_ring *ring = ring_data->ring;
	struct net_device *ndev = ring_data->napi.dev;
	struct netdev_queue *dev_queue;
	struct hns_nic_priv *priv = netdev_priv(ndev);
	int head;
	int bytes, pkts;

	NETIF_TX_LOCK(ring);

	head = readl_relaxed(ring->io_base + RCB_REG_HEAD);
	rmb(); /* make sure head is ready before touch any data */

	if (is_ring_empty(ring) || head == ring->next_to_clean) {
		NETIF_TX_UNLOCK(ring);
		return 0; /* no data to poll */
	}

	if (!is_valid_clean_head(ring, head)) {
		netdev_err(ndev, "wrong head (%d, %d-%d)\n", head,
			   ring->next_to_use, ring->next_to_clean);
		ring->stats.io_err_cnt++;
		NETIF_TX_UNLOCK(ring);
		return -EIO;
	}

	bytes = 0;
	pkts = 0;
	while (head != ring->next_to_clean) {
		hns_nic_reclaim_one_desc(ring, &bytes, &pkts);
		/* issue prefetch for next Tx descriptor */
		prefetch(&ring->desc_cb[ring->next_to_clean]);
	}

	NETIF_TX_UNLOCK(ring);

	dev_queue = netdev_get_tx_queue(ndev, ring_data->queue_index);
	netdev_tx_completed_queue(dev_queue, pkts, bytes);

	if (unlikely(priv->link && !netif_carrier_ok(ndev)))
		netif_carrier_on(ndev);

	if (unlikely(pkts && netif_carrier_ok(ndev) &&
		     (ring_space(ring) >= ring->max_desc_num_per_pkt * 2))) {
		/* Make sure that anybody stopping the queue after this
		 * sees the new next_to_clean.
		 */
		smp_mb();
		if (netif_tx_queue_stopped(dev_queue) &&
		    !test_bit(NIC_STATE_DOWN, &priv->state)) {
			netif_tx_wake_queue(dev_queue);
			ring->stats.restart_queue++;
		}
	}
	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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.