The patch titled
Subject: mm/userfaultfd: fail uffd-wp registeration if not supported
has been added to the -mm tree. Its filename is
mm-userfaultfd-fail-uffd-wp-registeration-if-not-supported.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-userfaultfd-fail-uffd-wp-registeration-if-not-supported.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-userfaultfd-fail-uffd-wp-registeration-if-not-supported.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: mm/userfaultfd: fail uffd-wp registeration if not supported
We should fail uffd-wp registration immediately if the arch does not even
have CONFIG_HAVE_ARCH_USERFAULTFD_WP defined. That'll block also relevant
ioctls on e.g. UFFDIO_WRITEPROTECT because that'll check against
VM_UFFD_WP, which can only be applied with a success registration.
Remove the WP feature bit too for those archs when handling UFFDIO_API
ioctl.
Link: https://lkml.kernel.org/r/20210428225030.9708-5-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: "Dr . David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Mina Almasry <almasrymina@xxxxxxxxxx>
Cc: Oliver Upton <oupton@xxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Wang Qing <wangqing@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/fs/userfaultfd.c~mm-userfaultfd-fail-uffd-wp-registeration-if-not-supported
+++ a/fs/userfaultfd.c
@@ -1304,8 +1304,12 @@ static int userfaultfd_register(struct u
vm_flags = 0;
if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING)
vm_flags |= VM_UFFD_MISSING;
- if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP)
+ if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) {
+#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP
+ goto out;
+#endif
vm_flags |= VM_UFFD_WP;
+ }
if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR) {
#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
goto out;
@@ -1943,6 +1947,9 @@ static int userfaultfd_api(struct userfa
#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS;
#endif
+#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP
+ uffdio_api.features &= ~UFFD_FEATURE_PAGEFAULT_FLAG_WP;
+#endif
uffdio_api.ioctls = UFFD_API_IOCTLS;
ret = -EFAULT;
if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-hugetlb-fix-f_seal_future_write.patch
mm-hugetlb-fix-cow-where-page-writtable-in-child.patch
mm-gup_benchmark-support-threading.patch
userfaultfd-selftests-use-user-mode-only.patch
userfaultfd-selftests-remove-the-time-check-on-delayed-uffd.patch
userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch
userfaultfd-selftests-only-dump-counts-if-mode-enabled.patch
userfaultfd-selftests-unify-error-handling.patch
mm-thp-simplify-copying-of-huge-zero-page-pmd-when-fork.patch
mm-userfaultfd-fix-uffd-wp-special-cases-for-fork.patch
mm-userfaultfd-fix-a-few-thp-pmd-missing-uffd-wp-bit.patch
mm-userfaultfd-fail-uffd-wp-registeration-if-not-supported.patch
mm-pagemap-export-uffd-wp-protection-information.patch
userfaultfd-selftests-add-pagemap-uffd-wp-test.patch
