static int hns_nic_poll_rx_skb(struct hns_nic_ring_data *ring_data,
			       struct sk_buff **out_skb, int *out_bnum)
{
	struct hnae_ring *ring = ring_data->ring;
	struct net_device *ndev = ring_data->napi.dev;
	struct hns_nic_priv *priv = netdev_priv(ndev);
	struct sk_buff *skb;
	struct hnae_desc *desc;
	struct hnae_desc_cb *desc_cb;
	unsigned char *va;
	int bnum, length, i;
	int pull_len;
	u32 bnum_flag;

	desc = &ring->desc[ring->next_to_clean];
	desc_cb = &ring->desc_cb[ring->next_to_clean];

	prefetch(desc);

	va = (unsigned char *)desc_cb->buf + desc_cb->page_offset;

	/* prefetch first cache line of first page */
	prefetch(va);
#if L1_CACHE_BYTES < 128
	prefetch(va + L1_CACHE_BYTES);
#endif

	skb = *out_skb = napi_alloc_skb(&ring_data->napi,
					HNS_RX_HEAD_SIZE);
	if (unlikely(!skb)) {
		netdev_err(ndev, "alloc rx skb fail\n");
		ring->stats.sw_err_cnt++;
		return -ENOMEM;
	}

	prefetchw(skb->data);
	length = le16_to_cpu(desc->rx.pkt_len);
	bnum_flag = le32_to_cpu(desc->rx.ipoff_bnum_pid_flag);
	priv->ops.get_rxd_bnum(bnum_flag, &bnum);
	*out_bnum = bnum;

	if (length <= HNS_RX_HEAD_SIZE) {
		memcpy(__skb_put(skb, length), va, ALIGN(length, sizeof(long)));

		/* we can reuse buffer as-is, just make sure it is local */
		if (likely(page_to_nid(desc_cb->priv) == numa_node_id()))
			desc_cb->reuse_flag = 1;
		else /* this page cannot be reused so discard it */
			put_page(desc_cb->priv);

		ring_ptr_move_fw(ring, next_to_clean);

		if (unlikely(bnum != 1)) { /* check err*/
			*out_bnum = 1;
			goto out_bnum_err;
		}
	} else {
		ring->stats.seg_pkt_cnt++;

		pull_len = hns_nic_get_headlen(va, bnum_flag, HNS_RX_HEAD_SIZE);
		memcpy(__skb_put(skb, pull_len), va,
		       ALIGN(pull_len, sizeof(long)));

		hns_nic_reuse_page(skb, 0, ring, pull_len, desc_cb);
		ring_ptr_move_fw(ring, next_to_clean);

		if (unlikely(bnum >= (int)MAX_SKB_FRAGS)) { /* check err*/
			*out_bnum = 1;
			goto out_bnum_err;
		}
		for (i = 1; i < bnum; i++) {
			desc = &ring->desc[ring->next_to_clean];
			desc_cb = &ring->desc_cb[ring->next_to_clean];

			hns_nic_reuse_page(skb, i, ring, 0, desc_cb);
			ring_ptr_move_fw(ring, next_to_clean);
		}
	}

	/* check except process, free skb and jump the desc */
	if (unlikely((!bnum) || (bnum > ring->max_desc_num_per_pkt))) {
out_bnum_err:
		*out_bnum = *out_bnum ? *out_bnum : 1; /* ntc moved,cannot 0*/
		netdev_err(ndev, "invalid bnum(%d,%d,%d,%d),%016llx,%016llx\n",
			   bnum, ring->max_desc_num_per_pkt,
			   length, (int)MAX_SKB_FRAGS,
			   ((u64 *)desc)[0], ((u64 *)desc)[1]);
		ring->stats.err_bd_num++;
		dev_kfree_skb_any(skb);
		return -EDOM;
	}

	bnum_flag = le32_to_cpu(desc->rx.ipoff_bnum_pid_flag);

	if (unlikely(!hnae_get_bit(bnum_flag, HNS_RXD_VLD_B))) {
		netdev_err(ndev, "no valid bd,%016llx,%016llx\n",
			   ((u64 *)desc)[0], ((u64 *)desc)[1]);
		ring->stats.non_vld_descs++;
		dev_kfree_skb_any(skb);
		return -EINVAL;
	}

	if (unlikely((!desc->rx.pkt_len) ||
		     hnae_get_bit(bnum_flag, HNS_RXD_DROP_B))) {
		ring->stats.err_pkt_len++;
		dev_kfree_skb_any(skb);
		return -EFAULT;
	}

	if (unlikely(hnae_get_bit(bnum_flag, HNS_RXD_L2E_B))) {
		ring->stats.l2_err++;
		dev_kfree_skb_any(skb);
		return -EFAULT;
	}

	ring->stats.rx_pkts++;
	ring->stats.rx_bytes += skb->len;

	/* indicate to upper stack if our hardware has already calculated
	 * the RX checksum
	 */
	hns_nic_rx_checksum(ring_data, skb, bnum_flag);

	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.