static struct sk_buff *receive_mergeable(struct net_device *dev,
					 struct virtnet_info *vi,
					 struct receive_queue *rq,
					 unsigned long ctx,
					 unsigned int len)
{
	void *buf = mergeable_ctx_to_buf_address(ctx);
	struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
	u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
	struct page *page = virt_to_head_page(buf);
	int offset = buf - page_address(page);
	unsigned int truesize = max(len, mergeable_ctx_to_buf_truesize(ctx));

	struct sk_buff *head_skb = page_to_skb(vi, rq, page, offset, len,
					       truesize);
	struct sk_buff *curr_skb = head_skb;

	if (unlikely(!curr_skb))
		goto err_skb;
	while (--num_buf) {
		int num_skb_frags;

		ctx = (unsigned long)virtqueue_get_buf(rq->vq, &len);
		if (unlikely(!ctx)) {
			pr_debug("%s: rx error: %d buffers out of %d missing\n",
				 dev->name, num_buf,
				 virtio16_to_cpu(vi->vdev,
						 hdr->num_buffers));
			dev->stats.rx_length_errors++;
			goto err_buf;
		}

		buf = mergeable_ctx_to_buf_address(ctx);
		page = virt_to_head_page(buf);

		num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
		if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
			struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC);

			if (unlikely(!nskb))
				goto err_skb;
			if (curr_skb == head_skb)
				skb_shinfo(curr_skb)->frag_list = nskb;
			else
				curr_skb->next = nskb;
			curr_skb = nskb;
			head_skb->truesize += nskb->truesize;
			num_skb_frags = 0;
		}
		truesize = max(len, mergeable_ctx_to_buf_truesize(ctx));
		if (curr_skb != head_skb) {
			head_skb->data_len += len;
			head_skb->len += len;
			head_skb->truesize += truesize;
		}
		offset = buf - page_address(page);
		if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
			put_page(page);
			skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
					     len, truesize);
		} else {
			skb_add_rx_frag(curr_skb, num_skb_frags, page,
					offset, len, truesize);
		}
	}

	ewma_add(&rq->mrg_avg_pkt_len, head_skb->len);
	return head_skb;

err_skb:
	put_page(page);
	while (--num_buf) {
		ctx = (unsigned long)virtqueue_get_buf(rq->vq, &len);
		if (unlikely(!ctx)) {
			pr_debug("%s: rx error: %d buffers missing\n",
				 dev->name, num_buf);
			dev->stats.rx_length_errors++;
			break;
		}
		page = virt_to_head_page(mergeable_ctx_to_buf_address(ctx));
		put_page(page);
	}
err_buf:
	dev->stats.rx_dropped++;
	dev_kfree_skb(head_skb);
	return NULL;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.