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 A825D4AC141 for ; Thu, 17 Sep 2026 21:09:56 +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=1789679399; cv=none; b=qfnDRqyOfjnLUaIL4ATH3jaJuDT2ssprHvMFvsorc7ReUXrucKUk2QNUDNEhXDxTOAMyNVU8gVLdmQIW+nFkfqeuLEAOracBCr/kCV390lWFgy1M6fwZlxUi7ytCI68Mta+0q3i7++JBWSrdnOoI4Oh/kJ36RRtGG+vMIVKU+Wk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789679399; c=relaxed/simple; bh=HvVtL2BMtcwtIQw0gqAHTvd/DmkgbOUTcsamKC1VOpI=; h=Date:To:From:Subject:Message-Id; b=j4w9m8/yp8fo0RaCwA2xogeGhMumPrW5dnx6ec8G2r09XspyiH13DOKaMU7t6+5ZKdPMLWrHkati8Vq/ScmzVLD8Uh04mtM6Qr78qiXxXC8US+mC3e3ImYlD6gl6DgTM8tpxPpbS7/DQK0k1mcWFQG8PzAkU8GwOk9WZ3z8MFq0= 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=s0b5lRKX; 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="s0b5lRKX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3DB031F0089A; Thu, 17 Sep 2026 21:09:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789679395; bh=TsxxRk2rsD4P2agekDbPZY1+bsN/QvQNzQco8LQcvlE=; h=Date:To:From:Subject; b=s0b5lRKXV3ny40K0e4xcyPN1u0sWxy+FjpKTxssD8+PU+bAKd50JzQ7shM3ngtbYR TYCK3yaNMzA4i8ZzeJYhlpsg9CHqqKCxlDV5HuNEkbyO3HqCGweR4HRuvKk9hhA0eO pKe+cnl4bnn5Rzi5tTNtT1DM2fb0wvr6++y97AX0= Date: Thu, 17 Sep 2026 14:09:54 -0700 To: mm-commits@vger.kernel.org,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-consistently-validate-vma-state-after-mmap-hooks.patch removed from -mm tree Message-Id: <20260917210955.3DB031F0089A@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: consistently validate VMA state after mmap[_prepare] hooks has been removed from the -mm tree. Its filename was mm-consistently-validate-vma-state-after-mmap-hooks.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: "Lorenzo Stoakes (ARM)" Subject: mm: consistently validate VMA state after mmap[_prepare] hooks Date: Mon, 14 Sep 2026 15:57:24 +0100 When the f_op->mmap_prepare or deprecated f_op->mmap hooks are invoked, the driver might have done something crazy that is not permitted by the kernel. Currently we check for three such cases in __mmap_new_file_vma(), but only if the legacy f_op->mmap hook is used: * Did sparc ADI result in invalid flags? * Did the driver alter vma->vm_start? * Did the driver make a file-backed mapping on a read-only file writable? Generalise these checks for both mmap_prepare and mmap and apply to all invocations of mmap_file(), the f_op->mmap and f_op->mmap_prepare handling in the core VMA code and the mmap_prepare compatibility layer. We also WARN_ON_ONCE() on these conditions as they are things that should simply not occur in the kernel and it's important to call it out when it does. We invoke mmap_prepare_validate() after mmap_action_prepare(), as mmap actions often manipulate state in the descriptor thus providing the final state the VMA will be derived from. Also call mmap_validate_vma_flags() in insert_vm_struct() to ensure that special regions which are inserted (such as a VDSO or VVAR) also satisfy the sanity checks. This way every VMA established through an mmap hook, whether via mmap() or the compatibility layer, or inserted via insert_vm_struct(), has been validated. brk() VMAs never pass through a driver hook and so need no such check. While we're here, also fixup a couple disjoint blocks of #ifdef CONFIG_MMU. Finally, update the VMA userland tests to reflect the change. Link: https://lore.kernel.org/20260914-b4-mmap-prepare-vma-flag-sanify-v2-4-7d9781ed5361@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton --- mm/internal.h | 49 +++++++++------ mm/util.c | 19 ++++- mm/vma.c | 96 +++++++++++++++++++++++++----- mm/vma.h | 24 ++++++- tools/testing/vma/include/dup.h | 10 +++ 5 files changed, 156 insertions(+), 42 deletions(-) --- a/mm/internal.h~mm-consistently-validate-vma-state-after-mmap-hooks +++ a/mm/internal.h @@ -214,6 +214,24 @@ static inline void *folio_raw_mapping(co } /* + * If the VMA has a close hook then close it, and since closing it might leave + * it in an inconsistent state which makes the use of any hooks suspect, clear + * them down by installing dummy empty hooks. + */ +static inline void vma_close(struct vm_area_struct *vma) +{ + if (vma->vm_ops && vma->vm_ops->close) { + vma->vm_ops->close(vma); + + /* + * The mapping is in an inconsistent state, and no further hooks + * may be invoked upon it. + */ + vma->vm_ops = &vma_dummy_vm_ops; + } +} + +/* * This is a file-backed mapping, and is about to be memory mapped - invoke its * mmap hook and safely handle error conditions. On error, VMA hooks will be * mutated. @@ -225,8 +243,11 @@ static inline void *folio_raw_mapping(co */ static inline int mmap_file(struct file *file, struct vm_area_struct *vma) { - int err = vfs_mmap(file, vma); + const unsigned long prev_start = vma->vm_start; + const vma_flags_t prev_flags = vma->flags; + int err; + err = vfs_mmap(file, vma); /* * Either we tried to call the file hook for mmap() and an error arose * or a driver set vma->vm_ops = NULL intending there to be no VMA @@ -239,26 +260,16 @@ static inline int mmap_file(struct file */ if (unlikely(err || !vma->vm_ops)) vma->vm_ops = &vma_dummy_vm_ops; + if (unlikely(err)) + return err; - return err; -} - -/* - * If the VMA has a close hook then close it, and since closing it might leave - * it in an inconsistent state which makes the use of any hooks suspect, clear - * them down by installing dummy empty hooks. - */ -static inline void vma_close(struct vm_area_struct *vma) -{ - if (vma->vm_ops && vma->vm_ops->close) { - vma->vm_ops->close(vma); - - /* - * The mapping is in an inconsistent state, and no further hooks - * may be invoked upon it. - */ - vma->vm_ops = &vma_dummy_vm_ops; + err = mmap_hook_validate(prev_start, &prev_flags, vma); + if (unlikely(err)) { + vma->vm_start = prev_start; + vma_close(vma); } + + return err; } /* unmap_vmas is in mm/memory.c */ --- a/mm/util.c~mm-consistently-validate-vma-state-after-mmap-hooks +++ a/mm/util.c @@ -1224,19 +1224,28 @@ EXPORT_SYMBOL(compat_set_desc_from_vma); int __compat_vma_mmap(struct vm_area_desc *desc, struct vm_area_struct *vma) { + struct vm_area_desc prev_desc; int err; + /* Derive state prior to mmap_prepare hook. */ + compat_set_desc_from_vma(&prev_desc, desc->file, vma); /* Perform any preparatory tasks for mmap action. */ err = mmap_action_prepare(desc); - if (err) { - if (desc->vm_file != vma->vm_file) - fput(desc->vm_file); - return err; - } + if (err) + goto err_put; + /* Check the caller did nothing crazy. */ + err = mmap_prepare_validate(&prev_desc, desc); + if (err) + goto err_put; /* Update the VMA from the descriptor. */ compat_set_vma_from_desc(vma, desc); /* Complete any specified mmap actions. */ return mmap_action_complete(vma, &desc->action, /*is_compat=*/true); + +err_put: + if (desc->vm_file != vma->vm_file) + fput(desc->vm_file); + return err; } EXPORT_SYMBOL(__compat_vma_mmap); --- a/mm/vma.c~mm-consistently-validate-vma-state-after-mmap-hooks +++ a/mm/vma.c @@ -2623,16 +2623,6 @@ static int __mmap_new_file_vma(struct mm return error; } - /* Drivers cannot alter the address of the VMA. */ - WARN_ON_ONCE(map->addr != vma->vm_start); - /* - * Drivers should not permit writability when previously it was - * disallowed. - */ - VM_WARN_ON_ONCE(!vma_flags_same_pair(&map->vma_flags, &vma->flags) && - !vma_flags_test(&map->vma_flags, VMA_MAYWRITE_BIT) && - vma_test(vma, VMA_MAYWRITE_BIT)); - map->vma_flags = vma->flags; return 0; @@ -2710,11 +2700,6 @@ static int __mmap_new_vma(struct mmap_st vma->flags = map->vma_flags; } -#ifdef CONFIG_SPARC64 - /* TODO: Fix SPARC ADI! */ - WARN_ON_ONCE(!arch_validate_flags(map->vm_flags)); -#endif - /* Lock the VMA since it is modified after insertion into VMA tree */ vma_start_write(vma); vma_iter_store_new(vmi, vma); @@ -2777,6 +2762,76 @@ static void __mmap_complete(struct mmap_ vma_set_page_prot(vma); } +/* Check to ensure that the VMA flags of a newly mapped VMA are sane. */ +static int mmap_validate_vma_flags(const vma_flags_t *flags) +{ +#ifdef CONFIG_SPARC64 + const vm_flags_t legacy_flags = vma_flags_to_legacy(*flags); + + /* TODO: Fix SPARC ADI! */ + if (WARN_ON_ONCE(!arch_validate_flags(legacy_flags))) + return -EINVAL; +#endif + + return 0; +} + +/* Check to ensure a driver hasn't done something crazy. */ +static int mmap_validate(unsigned long prev_start, + unsigned long curr_start, + const vma_flags_t *prev_flags, + const vma_flags_t *curr_flags) +{ + bool was_maywrite, is_maywrite; + + /* Drivers cannot alter the address of the VMA. */ + if (WARN_ON_ONCE(prev_start != curr_start)) + return -EINVAL; + + was_maywrite = vma_flags_test(prev_flags, VMA_MAYWRITE_BIT); + is_maywrite = vma_flags_test(curr_flags, VMA_MAYWRITE_BIT); + + /* A driver may not make a previously unwritable mapping writable. */ + if (WARN_ON_ONCE(!was_maywrite && is_maywrite)) + return -EINVAL; + + return mmap_validate_vma_flags(curr_flags); +} + +/** + * mmap_prepare_validate() - Ensure the driver hasn't violated invariants in its + * f_op->mmap_prepare hook. + * @prev_desc: The VMA descriptor prior to the mmap_prepare hook being called. + * @desc: The VMA descriptor after the mmap_prepare hook has been called. + * + * Returns: 0 on success, otherwise an error. + */ +int mmap_prepare_validate(const struct vm_area_desc *prev_desc, + const struct vm_area_desc *desc) +{ + return mmap_validate(prev_desc->start, desc->start, + &prev_desc->vma_flags, &desc->vma_flags); +} + +/** + * mmap_hook_validate() - Ensure the driver hasn't violated invariants in + * its f_op->mmap hook. + * @prev_start: The start of the mapping prior to the mmap hook. + * @prev_flags: The VMA flags set for the VMA prior to the mmap hook. + * @vma: The VMA after the hook has been applied. + * + * Returns: 0 on success, otherwise an error. + */ +int mmap_hook_validate(unsigned long prev_start, + const vma_flags_t *prev_flags, + const struct vm_area_struct *vma) +{ + const unsigned long start = vma->vm_start; + const vma_flags_t *flags = &vma->flags; + + return mmap_validate(prev_start, start, prev_flags, flags); +} + static int call_action_prepare(struct mmap_state *map, struct vm_area_desc *desc) { @@ -2803,6 +2858,7 @@ static int call_action_prepare(struct mm static int call_mmap_prepare(struct mmap_state *map, struct vm_area_desc *desc) { + const struct vm_area_desc prev_desc = *desc; int err; /* Invoke the hook. */ @@ -2828,6 +2884,11 @@ static int call_mmap_prepare(struct mmap if (err) return err; + /* Check the caller did nothing crazy. */ + err = mmap_prepare_validate(&prev_desc, desc); + if (err) + return err; + /* * MAP_PRIVATE-/dev/zero mappings are an ancient way of getting * anonymous mappings. Rather than allowing these mappings to be odd @@ -3455,10 +3516,15 @@ int __vm_munmap(unsigned long start, siz int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) { unsigned long charged = vma_pages(vma); + int err; if (find_vma_intersection(mm, vma->vm_start, vma->vm_end)) return -ENOMEM; + err = mmap_validate_vma_flags(&vma->flags); + if (err) + return err; + if (vma_test(vma, VMA_ACCOUNT_BIT) && security_vm_enough_memory_mm(mm, charged)) return -ENOMEM; --- a/mm/vma.h~mm-consistently-validate-vma-state-after-mmap-hooks +++ a/mm/vma.h @@ -782,14 +782,19 @@ struct vm_area_struct *vm_area_alloc(str struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig); void vm_area_free(struct vm_area_struct *vma); -/* vma_exec.c */ #ifdef CONFIG_MMU +int mmap_prepare_validate(const struct vm_area_desc *prev_desc, + const struct vm_area_desc *desc); + +int mmap_hook_validate(unsigned long prev_start, + const vma_flags_t *prev_flags, + const struct vm_area_struct *vma); + +/* vma_exec.c */ int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap, unsigned long *top_mem_p); int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift); -#endif -#ifdef CONFIG_MMU /* * Denies creating a writable executable mapping or gaining executable permissions. * @@ -838,6 +843,19 @@ static inline bool map_deny_write_exec(c return false; } +#else +static inline int mmap_prepare_validate(const struct vm_area_desc *prev_desc, + const struct vm_area_desc *desc) +{ + return 0; +} + +static inline int mmap_hook_validate(unsigned long prev_start, + const vma_flags_t *prev_flags, + const struct vm_area_struct *vma) +{ + return 0; +} #endif struct vm_area_struct *__install_special_mapping(struct mm_struct *mm, --- a/tools/testing/vma/include/dup.h~mm-consistently-validate-vma-state-after-mmap-hooks +++ a/tools/testing/vma/include/dup.h @@ -1359,15 +1359,25 @@ static inline int vfs_mmap_prepare(struc return file->f_op->mmap_prepare(desc); } +int mmap_prepare_validate(const struct vm_area_desc *prev_desc, + const struct vm_area_desc *desc); + static inline int __compat_vma_mmap(struct vm_area_desc *desc, struct vm_area_struct *vma) { + struct vm_area_desc prev_desc; int err; + /* Derive state prior to mmap_prepare hook. */ + compat_set_desc_from_vma(&prev_desc, desc->file, vma); /* Perform any preparatory tasks for mmap action. */ err = mmap_action_prepare(desc); if (err) return err; + /* Check the caller did nothing crazy. */ + err = mmap_prepare_validate(&prev_desc, desc); + if (err) + return err; /* Update the VMA from the descriptor. */ compat_set_vma_from_desc(vma, desc); /* Complete any specified mmap actions. */ _ Patches currently in -mm which might be from ljs@kernel.org are mm-vmpressure-remove-window-size-todo.patch tools-testing-selftests-mm-add-missing-gitignore-entries.patch mm-move-drivers-char-memc-to-mm-char-memc.patch mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch mm-huge_memory-zap-deposited-page-tables-after-an-rcu-grace-period.patch mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch mm-make-userland-page-table-freeing-rcu-safe.patch mm-change-the-contract-for-free_pgtables-update-docs.patch mm-vma-ensure-mmap_prepare-doesnt-set-actions-on-a-mergeable-vma.patch mm-make-map_kernel_pages_-internal-and-unexported.patch mm-vma-tidy-up-map-kernel-pages-enum-values.patch mm-add-mmap-action-for-discontiguous-kernel-page-mapping.patch docs-filesystems-update-mmap_prepare-docs-for-discontig-kernel-pgs.patch drivers-usb-mon-update-to-use-mmap_prepare-map-kernel-pages.patch infiniband-update-hfi1-to-use-remap_vmalloc_range.patch selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch alsa-pcm-use-vm_insert_page-to-map-pcm-status-page.patch bpf-arena-mark-arena_map_mmap-mappings-vm_mixedmap.patch mm-vma-add-vma_is_kernel_owned-predicates.patch mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-kernel-owned.patch mm-vma-add-and-use-vma__is_fixed_mapping.patch scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch fbdev-defio-assert-fbinfo_virtfb-drop-vm_io-add-vm_mixedmap.patch hsi-cmt_speech-convert-mmap-hook-to-mmap_prepare-refactor.patch mm-gup-error-out-early-on-vma_mayread_bit-vmas.patch uprobes-remove-vm_io-set-vm_mixedmap-for-mapped-kernel-pages.patch mm-mlock-clear-vma_locked_mask-over-mmap-callback.patch mm-mlock-eliminate-weird-vma_io_bit-abuse-and-simplify.patch mm-vma-enforce-that-only-kernel-owned-mappings-may-set-vma_io_bit.patch mm-remove-vma_io_bit-check-in-vma_is_kernel_owned.patch mm-remove-hugetlb_inlineh.patch mm-rename-is_vm_hugetlb_page-to-vma_is_hugetlb.patch mm-drop-some-redundant-checks-around-hugetlb-vmas.patch mm-madvise-update-is_valid_guard_vma-to-use-vma_can_merge.patch mm-vma-introduce-vma_is_persistent.patch mm-uffd-use-predicates-for-userfaultfd-checks.patch mm-madvise-use-predicates-for-madvise-madv_dofork.patch mm-eliminate-vma_special_flags-usage-when-hugetlb-explicitly-tested.patch mm-eliminate-vma_special_flags-check-in-lru_gen_look_around.patch mm-avoid-use-of-vma_special_flags-in-migrate_vma_setup.patch mm-eliminate-vm_special-vma_special_flags.patch fuse-dax-do-not-set-vm_mixedmap.patch mm-huge_memory-remove-vma_is_special_huge.patch mm-vma-introduce-and-use-vma_can_gup.patch mm-vma-const-ify-vma_assert_stabilised-and-associated-functions.patch mm-implement-and-use-vma_has_anon_rmap-silence-kcsan.patch mm-update-comments-to-refer-to-anon-rmap-rather-than-anon_vma.patch