static void netlink_skb_destructor(struct sk_buff *skb)
{
	if (is_vmalloc_addr(skb->head)) {
		if (!skb->cloned ||
		    !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
			vfree(skb->head);

		skb->head = NULL;
	}
	if (skb->sk != NULL)
		sock_rfree(skb);
}

The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations.