void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
			    unsigned long start, unsigned long end,
			    struct page *ref_page)
{
	struct mm_struct *mm = vma->vm_mm;
	unsigned long address;
	pte_t *ptep;
	pte_t pte;
	spinlock_t *ptl;
	struct page *page;
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
	const unsigned long mmun_start = start;	/* For mmu_notifiers */
	const unsigned long mmun_end   = end;	/* For mmu_notifiers */

	WARN_ON(!is_vm_hugetlb_page(vma));
	BUG_ON(start & ~huge_page_mask(h));
	BUG_ON(end & ~huge_page_mask(h));

	/*
	 * This is a hugetlb vma, all the pte entries should point
	 * to huge page.
	 */
	tlb_remove_check_page_size_change(tlb, sz);
	tlb_start_vma(tlb, vma);
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
	address = start;
	for (; address < end; address += sz) {
		ptep = huge_pte_offset(mm, address, sz);
		if (!ptep)
			continue;

		ptl = huge_pte_lock(h, mm, ptep);
		if (huge_pmd_unshare(mm, &address, ptep)) {
			spin_unlock(ptl);
			continue;
		}

		pte = huge_ptep_get(ptep);
		if (huge_pte_none(pte)) {
			spin_unlock(ptl);
			continue;
		}

		/*
		 * Migrating hugepage or HWPoisoned hugepage is already
		 * unmapped and its refcount is dropped, so just clear pte here.
		 */
		if (unlikely(!pte_present(pte))) {
			huge_pte_clear(mm, address, ptep, sz);
			spin_unlock(ptl);
			continue;
		}

		page = pte_page(pte);
		/*
		 * If a reference page is supplied, it is because a specific
		 * page is being unmapped, not a range. Ensure the page we
		 * are about to unmap is the actual page of interest.
		 */
		if (ref_page) {
			if (page != ref_page) {
				spin_unlock(ptl);
				continue;
			}
			/*
			 * Mark the VMA as having unmapped its page so that
			 * future faults in this VMA will fail rather than
			 * looking like data was lost
			 */
			set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
		}

		pte = huge_ptep_get_and_clear(mm, address, ptep);
		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
		if (huge_pte_dirty(pte))
			set_page_dirty(page);

		hugetlb_count_sub(pages_per_huge_page(h), mm);
		page_remove_rmap(page, true);

		spin_unlock(ptl);
		tlb_remove_page_size(tlb, page, huge_page_size(h));
		/*
		 * Bail out after unmapping reference page if supplied
		 */
		if (ref_page)
			break;
	}
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
	tlb_end_vma(tlb, vma);
}

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.