Commit 515778e2 authored by Peter Xu's avatar Peter Xu Committed by Andrew Morton
Browse files

mm/uffd: fix warning without PTE_MARKER_UFFD_WP compiled in 

When PTE_MARKER_UFFD_WP not configured, it's still possible to reach pte
marker code and trigger an warning. Add a few CONFIG_PTE_MARKER_UFFD_WP
ifdefs to make sure the code won't be reached when not compiled in.

Link: https://lkml.kernel.org/r/YzeR+R6b4bwBlBHh@x1n


Fixes: b1f9e876 ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Reported-by: default avatar <syzbot+2b9b4f0895be09a6dec3@syzkaller.appspotmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Edward Liaw <edliaw@google.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 28c5609f

mm/hugetlb.c

+4 −0
Original line number Diff line number Diff line
@@ -5096,6 +5096,7 @@ static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct 
		 * unmapped and its refcount is dropped, so just clear pte here.

		 */

		if (unlikely(!pte_present(pte))) {

#ifdef CONFIG_PTE_MARKER_UFFD_WP

			/*

			 * If the pte was wr-protected by uffd-wp in any of the

			 * swap forms, meanwhile the caller does not want to
@@ -5107,6 +5108,7 @@ static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct 
				set_huge_pte_at(mm, address, ptep,

						make_pte_marker(PTE_MARKER_UFFD_WP));

			else

#endif

				huge_pte_clear(mm, address, ptep, sz);

			spin_unlock(ptl);

			continue;
@@ -5135,11 +5137,13 @@ static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct 
		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);

		if (huge_pte_dirty(pte))

			set_page_dirty(page);

#ifdef CONFIG_PTE_MARKER_UFFD_WP

		/* Leave a uffd-wp pte marker if needed */

		if (huge_pte_uffd_wp(pte) &&

		    !(zap_flags & ZAP_FLAG_DROP_MARKER))

			set_huge_pte_at(mm, address, ptep,

					make_pte_marker(PTE_MARKER_UFFD_WP));

#endif

		hugetlb_count_sub(pages_per_huge_page(h), mm);

		page_remove_rmap(page, vma, true);

mm/memory.c

+2 −0
Original line number Diff line number Diff line
@@ -1393,10 +1393,12 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, 
			      unsigned long addr, pte_t *pte,

			      struct zap_details *details, pte_t pteval)

{

#ifdef CONFIG_PTE_MARKER_UFFD_WP

	if (zap_drop_file_uffd_wp(details))

		return;



	pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);

#endif

}



static unsigned long zap_pte_range(struct mmu_gather *tlb,

mm/mprotect.c

+2 −0
Original line number Diff line number Diff line
@@ -267,6 +267,7 @@ static unsigned long change_pte_range(struct mmu_gather *tlb, 
		} else {

			/* It must be an none page, or what else?.. */

			WARN_ON_ONCE(!pte_none(oldpte));

#ifdef CONFIG_PTE_MARKER_UFFD_WP

			if (unlikely(uffd_wp && !vma_is_anonymous(vma))) {

				/*

				 * For file-backed mem, we need to be able to
@@ -278,6 +279,7 @@ static unsigned long change_pte_range(struct mmu_gather *tlb, 
					   make_pte_marker(PTE_MARKER_UFFD_WP));

				pages++;

			}

#endif

		}

	} while (pte++, addr += PAGE_SIZE, addr != end);

	arch_leave_lazy_mmu_mode();