static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
	new->tstamp		= old->tstamp;
	new->dev		= old->dev;
	new->transport_header	= old->transport_header;
	new->network_header	= old->network_header;
	new->mac_header		= old->mac_header;
	new->inner_protocol	= old->inner_protocol;
	new->inner_transport_header = old->inner_transport_header;
	new->inner_network_header = old->inner_network_header;
	new->inner_mac_header = old->inner_mac_header;
	skb_dst_copy(new, old);
	skb_copy_hash(new, old);
	new->ooo_okay		= old->ooo_okay;
	new->no_fcs		= old->no_fcs;
	new->encapsulation	= old->encapsulation;
#ifdef CONFIG_XFRM
	new->sp			= secpath_get(old->sp);
#endif
	memcpy(new->cb, old->cb, sizeof(old->cb));
	new->csum		= old->csum;
	new->local_df		= old->local_df;
	new->pkt_type		= old->pkt_type;
	new->ip_summed		= old->ip_summed;
	skb_copy_queue_mapping(new, old);
	new->priority		= old->priority;
#if IS_ENABLED(CONFIG_IP_VS)
	new->ipvs_property	= old->ipvs_property;
#endif
	new->pfmemalloc		= old->pfmemalloc;
	new->protocol		= old->protocol;
	new->mark		= old->mark;
	new->skb_iif		= old->skb_iif;
	__nf_copy(new, old);
#ifdef CONFIG_NET_SCHED
	new->tc_index		= old->tc_index;
#ifdef CONFIG_NET_CLS_ACT
	new->tc_verd		= old->tc_verd;
#endif
#endif
	new->vlan_proto		= old->vlan_proto;
	new->vlan_tci		= old->vlan_tci;

	skb_copy_secmark(new, old);

#ifdef CONFIG_NET_RX_BUSY_POLL
	new->napi_id	= old->napi_id;
#endif
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.