static void update_memslots(struct kvm_memslots *slots,
			    struct kvm_memory_slot *new)
{
	int id = new->id;
	int i = slots->id_to_index[id];
	struct kvm_memory_slot *mslots = slots->memslots;

	WARN_ON(mslots[i].id != id);
	if (!new->npages) {
		WARN_ON(!mslots[i].npages);
		if (mslots[i].npages)
			slots->used_slots--;
	} else {
		if (!mslots[i].npages)
			slots->used_slots++;
	}

	while (i < KVM_MEM_SLOTS_NUM - 1 &&
	       new->base_gfn <= mslots[i + 1].base_gfn) {
		if (!mslots[i + 1].npages)
			break;
		mslots[i] = mslots[i + 1];
		slots->id_to_index[mslots[i].id] = i;
		i++;
	}

	/*
	 * The ">=" is needed when creating a slot with base_gfn == 0,
	 * so that it moves before all those with base_gfn == npages == 0.
	 *
	 * On the other hand, if new->npages is zero, the above loop has
	 * already left i pointing to the beginning of the empty part of
	 * mslots, and the ">=" would move the hole backwards in this
	 * case---which is wrong.  So skip the loop when deleting a slot.
	 */
	if (new->npages) {
		while (i > 0 &&
		       new->base_gfn >= mslots[i - 1].base_gfn) {
			mslots[i] = mslots[i - 1];
			slots->id_to_index[mslots[i].id] = i;
			i--;
		}
	} else
		WARN_ON_ONCE(i != slots->used_slots);

	mslots[i] = *new;
	slots->id_to_index[mslots[i].id] = i;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.