From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E70F15A864; Thu, 18 Jun 2026 18:34:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781807684; cv=none; b=W+AZZGdIomh7pDljZvDPsnfyPuMGcRtzV8vWIfet30/WPP6OMb7d1TOYDhxhOYwX6iA+J6Rey3XzbCeRyJ1LB9iWoJdl7kuGN2wUY3Wq5Xhp8pXPs7xRfkkQmTIH7ZSmCtEExMvb2WzlDrHf6cm7PHy/ji5xBi+YhKoE147jgwk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781807684; c=relaxed/simple; bh=63vlxuxlUNvwRyOcR8bZBL+gdC7dePKv0Lsd4RjqI1I=; h=Date:To:From:Subject:Message-Id; b=epEAAnDrqy0w9EzNzclo+ExS6KW0fXQZitjod9R7sJNsF5kS6ftPxhgZr6V3OIyPmY63fs7kfgYnpHMvJzVWV61JML0s97YtfdOJT8YtDPeldz4Rd2wlmYR2bT5hP/ytf296FbtCDytSFR2lrahk7kGSPUNOTqfiBfWD2LMlvbo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=tJEQAHgf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="tJEQAHgf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BBCD71F000E9; Thu, 18 Jun 2026 18:34:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1781807682; bh=vJOBl6rNEM7wV46rhbsBVn9UTO0qItXWD97j02VoBoM=; h=Date:To:From:Subject; b=tJEQAHgfQN93AUexMb71tjeckaa8sqQDK6EUhT3oQzLPt/++pKVFNDIPNmHeIJeiJ RF2I8+f1qxGZqtP0eFAEEhlPq5fiB2O/YMSDhzQX5Ct6yqSYU1H9BYQUdieHjP0MOC S4S4o5tft2sG4yUVxNWRkok7YaPwz2DY0HO2YdPI= Date: Thu, 18 Jun 2026 11:34:41 -0700 To: mm-commits@vger.kernel.org,vladimirelitokarev@gmail.com,viro@zeniv.linux.org.uk,torvalds@linuxfoundation.org,stable@vger.kernel.org,peterx@redhat.com,oleg@redhat.com,jack@suse.cz,david@kernel.org,brauner@kernel.org,rppt@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + userfaultfd-prevent-registration-of-special-vmas.patch added to mm-hotfixes-unstable branch Message-Id: <20260618183442.BBCD71F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: userfaultfd: prevent registration of special VMAs has been added to the -mm mm-hotfixes-unstable branch. Its filename is userfaultfd-prevent-registration-of-special-vmas.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/userfaultfd-prevent-registration-of-special-vmas.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: "Mike Rapoport (Microsoft)" Subject: userfaultfd: prevent registration of special VMAs Date: Thu, 18 Jun 2026 12:50:17 +0300 Vova Tokarev says: userfaultfd allows registration on shadow stack VMAs. With userfaultfd access, you can register on the shadow stack, discard a page ... and inject a page with chosen return addresses via UFFDIO_COPY. Update vma_can_userfault() to reject VM_SHADOW_STACK. While on it, also reject VM_SPECIAL so that if a driver would implement vm_uffd_ops, it wouldn't be possible to register special VMAs with userfaultfd. Since VM_SPECIAL includes VM_DONTEXPAND which is set but hugetlb, exclude hugetlb VMAs from the check for VM_SPECIAL. Link: https://lore.kernel.org/20260618095017.2553004-1-rppt@kernel.org Fixes: 54007f818206 ("mm: Introduce VM_SHADOW_STACK for shadow stack memory") Signed-off-by: Mike Rapoport (Microsoft) Reported-by: vova tokarev Acked-by: David Hildenbrand (Arm) Cc: Al Viro Cc: Christian Brauner Cc: Jan Kara Cc: Linus Torvalds Cc: Mike Rapoport Cc: Oleg Nesterov Cc: Peter Xu Cc: Signed-off-by: Andrew Morton --- mm/userfaultfd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/userfaultfd.c~userfaultfd-prevent-registration-of-special-vmas +++ a/mm/userfaultfd.c @@ -2095,7 +2095,10 @@ bool vma_can_userfault(struct vm_area_st { const struct vm_uffd_ops *ops = vma_uffd_ops(vma); - if (vma->vm_flags & VM_DROPPABLE) + if (vma->vm_flags & (VM_DROPPABLE | VM_SHADOW_STACK)) + return false; + + if (!is_vm_hugetlb_page(vma) && (vma->vm_flags & VM_SPECIAL)) return false; vm_flags &= __VM_UFFD_FLAGS; _ Patches currently in -mm which might be from rppt@kernel.org are userfaultfd-prevent-registration-of-special-vmas.patch selftests-mm-hugetlb-read-hwpoison-add-sigbus-handler.patch selftests-mm-migration-dont-assume-huge-page-is-twomeg.patch selftests-mm-migration-make-nthreads-represent-number-of-working-threads.patch selftests-mm-migration-properly-cleanup-forked-processes.patch selftests-mm-run_vmtestssh-dont-gate-thp-and-ksm-tests-on-have_hugepages.patch selftests-mm-merge-map_hugetlb-into-hugepage-mmap.patch selftests-mm-rename-hugepage-tests-to-hugetlb.patch selftests-mm-hugetlb-shm-use-kselftest-framework.patch selftests-mm-hugetlb-vmemmap-use-kselftest-framework.patch selftests-mm-hugetlb-madvise-use-kselftest-framework.patch selftests-mm-hugetlb_madv_vs_map-use-kselftest-framework.patch selftests-mm-hugetlb-read-hwpoison-use-kselftest-framework.patch selftests-mm-khugepaged-group-tests-in-an-array.patch selftests-mm-khugepaged-use-ksefltest-framework.patch selftests-mm-ksm_tests-use-kselftest-framework.patch selftests-mm-protection_keys-use-descriptive-test-names-in-the-output.patch selftests-mm-protection_keys-use-kselftest-framework.patch selftests-mm-uffd-common-use-kselftest-framework.patch selftests-mm-uffd-stress-use-kselftest-framework.patch selftests-mm-uffd-unit-tests-use-kselftest-framework.patch selftests-mm-va_high_addr_switch-use-kselftest-framework.patch selftests-mm-add-atexit-and-signal-handlers-to-thp_settings.patch selftests-mm-rename-thp_settings-to-hugepage_settings.patch selftests-mm-move-hugetlb-helpers-to-hugepage_settings.patch selftests-mm-hugepage_settings-use-unsigned-long-in-detect_hugetlb_page_size.patch selftests-mm-hugepage_settings-add-apis-to-get-and-set-nr_hugepages.patch selftests-mm-hugepage_settings-rename-and-rework-get_free_hugepages.patch selftests-mm-hugepage_settings-add-apis-for-hugetlb-setup-and-teardown.patch selftests-mm-move-read_file-read_num-and-write_num-to-vm_util.patch selftests-mm-vm_util-add-helpers-to-set-and-restore-shm-limits.patch selftests-mm-compaction_test-use-hugetlb-helpers.patch selftests-mm-cow-add-setup-of-hugetlb-pages.patch selftests-mm-gup_longterm-add-setup-of-hugetlb-pages.patch selftests-mm-gup_test-add-setup-of-hugetlb-pages.patch selftests-mm-hmm-tests-add-setup-of-hugetlb-pages.patch selftests-mm-hugepage_dio-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb_fault_after_madv-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb-madvise-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb_madv_vs_map-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb-mmap-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb-mremap-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb-shm-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb-soft-offline-add-setup-of-hugetlb-pages.patch selftests-mm-hugetlb-vmemmap-add-setup-of-hugetlb-pages.patch selftests-mm-migration-add-setup-of-hugetlb-pages.patch selftests-mm-pagemap_ioctl-add-setup-of-hugetlb-pages.patch selftests-mm-protection_keys-use-library-code-for-hugetlb-setup.patch selftests-mm-thuge-gen-add-setup-of-hugetlb-pages.patch selftests-mm-uffd-stress-use-hugetlb_save-and-alloc-huge-pages.patch selftests-mm-uffd-unit-tests-add-setup-of-hugetlb-pages.patch selftests-mm-uffd-wp-mremap-add-setup-of-hugetlb-pages.patch selftests-mm-va_high_addr_switch-add-setup-of-hugetlb-pages.patch selftests-mm-va_high_addr_switchsh-drop-huge-pages-setup.patch selftests-mm-run_vmtestssh-free-memory-if-available-memory-is-low.patch selftests-mm-run_vmtestssh-drop-detection-and-setup-of-hugetlb.patch