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...
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