linux/Documentation/mm
Ruihan Li 81a31a860b mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM
Without EXCLUSIVE_SYSTEM_RAM, users are allowed to map arbitrary
physical memory regions into the userspace via /dev/mem. At the same
time, pages may change their properties (e.g., from anonymous pages to
named pages) while they are still being mapped in the userspace, leading
to "corruption" detected by the page table check.

To avoid these false positives, this patch makes PAGE_TABLE_CHECK
depends on EXCLUSIVE_SYSTEM_RAM. This dependency is understandable
because PAGE_TABLE_CHECK is a hardening technique but /dev/mem without
STRICT_DEVMEM (i.e., !EXCLUSIVE_SYSTEM_RAM) is itself a security
problem.

Even with EXCLUSIVE_SYSTEM_RAM, I/O pages may be still allowed to be
mapped via /dev/mem. However, these pages are always considered as named
pages, so they won't break the logic used in the page table check.

Cc: <stable@vger.kernel.org> # 5.17
Signed-off-by: Ruihan Li <lrh2000@pku.edu.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/r/20230515130958.32471-4-lrh2000@pku.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-05-29 16:14:28 +01:00
..
damon Docs/mm/damon: add a maintainer-profile for DAMON 2023-02-02 22:32:52 -08:00
active_mm.rst lazy tlb: allow lazy tlb mm refcounting to be configurable 2023-03-28 16:20:08 -07:00
arch_pgtable_helpers.rst mm/debug_vm_pgtable: replace pte_mkhuge() with arch_make_huge_pte() 2023-03-28 16:20:11 -07:00
balance.rst - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
bootmem.rst
free_page_reporting.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
frontswap.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
highmem.rst - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
hmm.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
hugetlbfs_reserv.rst docs/mm: hugetlbfs_reserv: fix a reference to a file that doesn't exist 2023-03-07 10:31:49 -07:00
hwpoison.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
index.rst Docs/subsystem-apis: Remove '[The ]Linux' prefixes from titles of listed documents 2023-01-24 15:27:08 -07:00
ksm.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
memory-model.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
mmu_notifier.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
multigen_lru.rst mm: multi-gen LRU: improve design doc 2023-03-28 16:20:07 -07:00
numa.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
oom.rst
overcommit-accounting.rst
page_allocation.rst
page_cache.rst
page_frags.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
page_migration.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
page_owner.rst - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
page_reclaim.rst docs/mm: Physical Memory: remove useless markup 2023-02-02 10:18:04 -07:00
page_table_check.rst mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM 2023-05-29 16:14:28 +01:00
page_tables.rst
physical_memory.rst docs/mm: Physical Memory: Fix grammar 2023-04-11 16:16:50 -06:00
process_addrs.rst
remap_file_pages.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
shmfs.rst
slab.rst
slub.rst - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
split_page_table_lock.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
swap.rst
transhuge.rst - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
unevictable-lru.rst shmem: add support to ignore swap 2023-03-28 16:20:15 -07:00
vmalloc.rst
vmalloced-kernel-stacks.rst
vmemmap_dedup.rst mm: hugetlb_vmemmap: move code comments to vmemmap_dedup.rst 2022-08-08 18:06:43 -07:00
z3fold.rst docs/mm: remove useless markup 2023-02-02 10:18:05 -07:00
zsmalloc.rst zsmalloc: document freeable stats 2023-04-05 18:06:23 -07:00