+ mm-uffd-fix-vma-check-on-userfault-for-wp.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/uffd: fix vma check on userfault for wp
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-uffd-fix-vma-check-on-userfault-for-wp.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-uffd-fix-vma-check-on-userfault-for-wp.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Peter Xu <peterx@redhat.com>
Subject: mm/uffd: fix vma check on userfault for wp
Date: Mon, 24 Oct 2022 15:33:35 -0400

We used to have a report that pte-marker code can be reached even when
uffd-wp is not compiled in for file memories, here:

https://lore.kernel.org/all/YzeR+R6b4bwBlBHh@x1n/T/#u

I just got time to revisit this and found that the root cause is we simply
messed up with the vma check, so that for !PTE_MARKER_UFFD_WP system, we
will allow UFFDIO_REGISTER of MINOR & WP upon shmem as the check was
wrong:

    if (vm_flags & VM_UFFD_MINOR)
        return is_vm_hugetlb_page(vma) || vma_is_shmem(vma);

Where we'll allow anything to pass on shmem as long as minor mode is
requested.

Axel did it right when introducing minor mode but I messed it up in
b1f9e876862d when moving code around.  Fix it.

Link: https://lkml.kernel.org/r/20221024193336.1233616-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20221024193336.1233616-2-peterx@redhat.com
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/userfaultfd_k.h |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/include/linux/userfaultfd_k.h~mm-uffd-fix-vma-check-on-userfault-for-wp
+++ a/include/linux/userfaultfd_k.h
@@ -146,9 +146,9 @@ static inline bool userfaultfd_armed(str
 static inline bool vma_can_userfault(struct vm_area_struct *vma,
 				     unsigned long vm_flags)
 {
-	if (vm_flags & VM_UFFD_MINOR)
-		return is_vm_hugetlb_page(vma) || vma_is_shmem(vma);
-
+	if ((vm_flags & VM_UFFD_MINOR) &&
+	    (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
+		return false;
 #ifndef CONFIG_PTE_MARKER_UFFD_WP
 	/*
 	 * If user requested uffd-wp but not enabled pte markers for
_

Patches currently in -mm which might be from peterx@redhat.com are

mm-uffd-fix-vma-check-on-userfault-for-wp.patch
revert-mm-uffd-fix-warning-without-pte_marker_uffd_wp-compiled-in.patch
selftests-vm-use-memfd-for-uffd-hugetlb-tests.patch
selftests-vm-use-memfd-for-hugetlb-madvise-test.patch
selftests-vm-use-memfd-for-hugepage-mremap-test.patch
selftests-vm-drop-mnt-point-for-hugetlb-in-run_vmtestssh.patch
mm-hugetlb-unify-clearing-of-restorereserve-for-private-pages.patch