struct sk_buff *skb_segment(struct sk_buff *head_skb,
			    netdev_features_t features)
{
	struct sk_buff *segs = NULL;
	struct sk_buff *tail = NULL;
	struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
 	skb_frag_t *frag = skb_shinfo(head_skb)->frags;
 	unsigned int mss = skb_shinfo(head_skb)->gso_size;
 	unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
	struct sk_buff *frag_skb = head_skb;
 	unsigned int offset = doffset;
 	unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
 	unsigned int headroom;
	unsigned int len;
	__be16 proto;
	bool csum;
	int sg = !!(features & NETIF_F_SG);
	int nfrags = skb_shinfo(head_skb)->nr_frags;
	int err = -ENOMEM;
	int i = 0;
	int pos;

	proto = skb_network_protocol(head_skb);
	if (unlikely(!proto))
		return ERR_PTR(-EINVAL);

	csum = !!can_checksum_protocol(features, proto);
	__skb_push(head_skb, doffset);
	headroom = skb_headroom(head_skb);
	pos = skb_headlen(head_skb);

	do {
		struct sk_buff *nskb;
		skb_frag_t *nskb_frag;
		int hsize;
		int size;

		len = head_skb->len - offset;
		if (len > mss)
			len = mss;

		hsize = skb_headlen(head_skb) - offset;
		if (hsize < 0)
			hsize = 0;
		if (hsize > len || !sg)
			hsize = len;

		if (!hsize && i >= nfrags && skb_headlen(list_skb) &&
		    (skb_headlen(list_skb) == len || sg)) {
			BUG_ON(skb_headlen(list_skb) > len);

 			i = 0;
 			nfrags = skb_shinfo(list_skb)->nr_frags;
 			frag = skb_shinfo(list_skb)->frags;
			frag_skb = list_skb;
 			pos += skb_headlen(list_skb);
 
 			while (pos < offset + len) {
				BUG_ON(i >= nfrags);

				size = skb_frag_size(frag);
				if (pos + size > offset + len)
					break;

				i++;
				pos += size;
				frag++;
			}

			nskb = skb_clone(list_skb, GFP_ATOMIC);
			list_skb = list_skb->next;

			if (unlikely(!nskb))
				goto err;

			if (unlikely(pskb_trim(nskb, len))) {
				kfree_skb(nskb);
				goto err;
			}

			hsize = skb_end_offset(nskb);
			if (skb_cow_head(nskb, doffset + headroom)) {
				kfree_skb(nskb);
				goto err;
			}

			nskb->truesize += skb_end_offset(nskb) - hsize;
			skb_release_head_state(nskb);
			__skb_push(nskb, doffset);
		} else {
			nskb = __alloc_skb(hsize + doffset + headroom,
					   GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
					   NUMA_NO_NODE);

			if (unlikely(!nskb))
				goto err;

			skb_reserve(nskb, headroom);
			__skb_put(nskb, doffset);
		}

		if (segs)
			tail->next = nskb;
		else
			segs = nskb;
		tail = nskb;

		__copy_skb_header(nskb, head_skb);
		nskb->mac_len = head_skb->mac_len;

		skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);

		skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
						 nskb->data - tnl_hlen,
						 doffset + tnl_hlen);

		if (nskb->len == len + doffset)
			goto perform_csum_check;

		if (!sg) {
			nskb->ip_summed = CHECKSUM_NONE;
			nskb->csum = skb_copy_and_csum_bits(head_skb, offset,
							    skb_put(nskb, len),
							    len, 0);
			continue;
		}

		nskb_frag = skb_shinfo(nskb)->frags;

		skb_copy_from_linear_data_offset(head_skb, offset,
						 skb_put(nskb, hsize), hsize);

		skb_shinfo(nskb)->tx_flags = skb_shinfo(head_skb)->tx_flags &
			SKBTX_SHARED_FRAG;

		while (pos < offset + len) {
			if (i >= nfrags) {
				BUG_ON(skb_headlen(list_skb));

 				i = 0;
 				nfrags = skb_shinfo(list_skb)->nr_frags;
 				frag = skb_shinfo(list_skb)->frags;
				frag_skb = list_skb;
 
 				BUG_ON(!nfrags);
 
				list_skb = list_skb->next;
			}

			if (unlikely(skb_shinfo(nskb)->nr_frags >=
				     MAX_SKB_FRAGS)) {
				net_warn_ratelimited(
					"skb_segment: too many frags: %u %u\n",
					pos, mss);
 				goto err;
 			}
 
			if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
				goto err;

 			*nskb_frag = *frag;
 			__skb_frag_ref(nskb_frag);
 			size = skb_frag_size(nskb_frag);

			if (pos < offset) {
				nskb_frag->page_offset += offset - pos;
				skb_frag_size_sub(nskb_frag, offset - pos);
			}

			skb_shinfo(nskb)->nr_frags++;

			if (pos + size <= offset + len) {
				i++;
				frag++;
				pos += size;
			} else {
				skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
				goto skip_fraglist;
			}

			nskb_frag++;
		}

skip_fraglist:
		nskb->data_len = len - hsize;
		nskb->len += nskb->data_len;
		nskb->truesize += nskb->data_len;

perform_csum_check:
		if (!csum) {
			nskb->csum = skb_checksum(nskb, doffset,
						  nskb->len - doffset, 0);
			nskb->ip_summed = CHECKSUM_NONE;
		}
	} while ((offset += len) < head_skb->len);

	return segs;

err:
	kfree_skb_list(segs);
	return ERR_PTR(err);
}

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.