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Lance Yang bb1c19636a mm/secretmem: fix use-after-free race in fault handler 
[ Upstream commit 6f86d0534f ]

When a page fault occurs in a secret memory file created with
`memfd_secret(2)`, the kernel will allocate a new page for it, mark the
underlying page as not-present in the direct map, and add it to the file
mapping.

If two tasks cause a fault in the same page concurrently, both could end
up allocating a page and removing the page from the direct map, but only
one would succeed in adding the page to the file mapping.  The task that
failed undoes the effects of its attempt by (a) freeing the page again
and (b) putting the page back into the direct map.  However, by doing
these two operations in this order, the page becomes available to the
allocator again before it is placed back in the direct mapping.

If another task attempts to allocate the page between (a) and (b), and the
kernel tries to access it via the direct map, it would result in a
supervisor not-present page fault.

Fix the ordering to restore the direct map before the page is freed.

Link: https://lkml.kernel.org/r/20251031120955.92116-1-lance.yang@linux.dev
Fixes: 1507f51255 ("mm: introduce memfd_secret system call to create "secret" memory areas")
Signed-off-by: Lance Yang <lance.yang@linux.dev>
Reported-by: Google Big Sleep <big-sleep-vuln-reports@google.com>
Closes: https://lore.kernel.org/linux-mm/CAEXGt5QeDpiHTu3K9tvjUTPqo+d-=wuCNYPa+6sWKrdQJ-ATdg@mail.gmail.com/
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 6f86d0534f)
[rppt: replaced folio with page in the patch and in the changelog]
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-12-07 06:09:32 +09:00
..
damon mm/damon/vaddr: fix issue in damon_va_evenly_split_region() 2024-12-14 19:51:45 +01:00
kasan mm: introduce and use {pgd,p4d}_populate_kernel() 2025-10-02 13:38:59 +02:00
kfence kfence: skip __GFP_THISNODE allocations on NUMA systems 2025-03-13 12:50:50 +01:00
backing-dev.c writeback, cgroup: fix null-ptr-deref write in bdi_split_work_to_wbs 2023-05-11 23:00:18 +09:00
balloon_compaction.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
bootmem_info.c bootmem: remove the vmemmap pages from kmemleak in put_page_bootmem 2022-08-31 17:16:48 +02:00
cleancache.c Driver Core and debugfs changes for 5.3-rc1 2019-07-12 12:24:03 -07:00
cma.c mm/cma: drop incorrect alignment check in cma_init_reserved_mem 2024-07-05 09:14:13 +02:00
cma.h mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
cma_debug.c mm/cma: change cma mutex to irq safe spinlock 2021-05-05 11:27:21 -07:00
cma_sysfs.c mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
compaction.c mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations 2024-04-10 16:19:37 +02:00
debug.c mm/debug: sync up latest migrate_reason to migrate_reason_names 2021-09-24 16:13:35 -07:00
debug_page_ref.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
debug_vm_pgtable.c mm/debug_vm_pgtable: clear page table entries at destroy_args() 2025-08-28 16:24:34 +02:00
dmapool.c mm/dmapool: use DEVICE_ATTR_RO macro 2021-06-29 10:53:52 -07:00
early_ioremap.c mm/early_ioremap.c: remove redundant early_ioremap_shutdown() 2021-09-08 11:50:24 -07:00
fadvise.c mm, fadvise: improve the expensive remote LRU cache draining after FADV_DONTNEED 2020-10-13 18:38:29 -07:00
failslab.c mm/failslab.c: by default, do not fail allocations with direct reclaim only 2019-07-12 11:05:43 -07:00
filemap.c mm: drop the assumption that VM_SHARED always implies writable 2025-08-28 16:24:30 +02:00
frontswap.c mm/mempool: minor coding style tweaks 2021-05-05 11:27:27 -07:00
gup.c mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() 2025-05-02 07:44:13 +02:00
gup_test.c selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages 2021-05-05 11:27:26 -07:00
gup_test.h selftests/vm: gup_test: fix test flag 2021-05-05 11:27:26 -07:00
highmem.c highmem: fix checks in __kmap_local_sched_{in,out} 2022-04-13 20:59:21 +02:00
hmm.c mm/hmm: move pmd_to_hmm_pfn_flags() to the respective #ifdeffery 2025-08-28 16:24:14 +02:00
huge_memory.c mm/huge_memory: fix dereferencing invalid pmd migration entry 2025-06-27 11:05:37 +01:00
hugetlb.c mm: hugetlb: avoid soft lockup when mprotect to large memory area 2025-10-19 16:21:38 +02:00
hugetlb_cgroup.c hugetlb: make free_huge_page irq safe 2021-05-05 11:27:22 -07:00
hugetlb_vmemmap.c mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON 2021-06-30 20:47:26 -07:00
hugetlb_vmemmap.h mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate 2021-06-30 20:47:25 -07:00
hwpoison-inject.c mm/hwpoison: avoid the impact of hwpoison_filter() return value on mce handler 2022-07-12 16:35:05 +02:00
init-mm.c mm: add setup_initial_init_mm() helper 2021-07-08 11:48:21 -07:00
internal.h mm: unconditionally close VMAs on error 2024-12-14 19:50:38 +01:00
interval_tree.c mm/interval_tree: add comments to improve code readability 2021-04-30 11:20:38 -07:00
io-mapping.c mm: add a io_mapping_map_user helper 2021-04-30 11:20:39 -07:00
ioremap.c mm: move ioremap_page_range to vmalloc.c 2021-09-08 11:50:24 -07:00
Kconfig kmap_local: don't assume kmap PTEs are linear arrays in memory 2021-11-25 09:48:43 +01:00
Kconfig.debug mm, page_poison: remove CONFIG_PAGE_POISONING_ZERO 2020-12-15 12:13:46 -08:00
khugepaged.c mm/khugepaged: fix the address passed to notifier on testing young 2025-10-02 13:39:01 +02:00
kmemleak.c mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock 2025-08-28 16:24:27 +02:00
ksm.c mm/ksm: remove old GCC 4.9+ check 2021-09-13 10:18:28 -07:00
list_lru.c mm: vmscan: consolidate shrinker_maps handling code 2021-05-05 11:27:23 -07:00
maccess.c maccess: Fix writing offset in case of fault in strncpy_from_kernel_nofault() 2022-11-26 09:24:47 +01:00
madvise.c mm: drop the assumption that VM_SHARED always implies writable 2025-08-28 16:24:30 +02:00
Makefile mm: introduce Data Access MONitor (DAMON) 2021-09-08 11:50:24 -07:00
mapping_dirty_helpers.c mm/mapping_dirty_helpers: remove double Note in kerneldoc 2021-07-01 11:06:02 -07:00
memblock.c memblock: allow to specify flags with memblock_add_node() 2023-12-20 15:17:33 +01:00
memcontrol.c memcg: always call cond_resched() after fn() 2025-06-04 14:38:06 +02:00
memfd.c mm: reinstate ability to map write-sealed memfd mappings read-only 2025-08-28 16:24:30 +02:00
memory-failure.c mm/memory-failure: fix VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory 2025-10-02 13:39:05 +02:00
memory.c mm: fix apply_to_existing_page_range() 2025-05-02 07:44:24 +02:00
memory_hotplug.c memblock: allow to specify flags with memblock_add_node() 2023-12-20 15:17:33 +01:00
mempolicy.c mm/numa_balancing: teach mpol_to_str about the balancing mode 2024-08-19 05:45:17 +02:00
mempool.c kasan: use separate (un)poison implementation for integrated init 2021-06-04 19:32:21 +01:00
memremap.c mm/memremap.c: map FS_DAX device memory as decrypted 2022-11-16 09:58:27 +01:00
memtest.c memtest: use {READ,WRITE}_ONCE in memory scanning 2024-04-10 16:18:42 +02:00
migrate.c mm/migrate_device: don't add folio to be freed to LRU in migrate_device_finalize() 2025-10-02 13:39:14 +02:00
mincore.c inode: make init and permission helpers idmapped mount aware 2021-01-24 14:27:16 +01:00
mlock.c mm/mlock: fix potential imbalanced rlimit ucounts adjustment 2022-05-15 20:18:53 +02:00
mm_init.c include/linux/page-flags-layout.h: cleanups 2021-04-30 11:20:42 -07:00
mmap.c mm: reinstate ability to map write-sealed memfd mappings read-only 2025-08-28 16:24:30 +02:00
mmap_lock.c mm: mmap_lock: replace get_memcg_path_buf() with on-stack buffer 2024-08-19 05:45:10 +02:00
mmu_gather.c mm/khugepaged: fix GUP-fast interaction by sending IPI 2022-12-14 11:37:17 +01:00
mmu_notifier.c mm/mmu_notifier.c: fix race in mmu_interval_notifier_remove() 2022-04-27 14:38:58 +02:00
mmzone.c mm/lru: replace pgdat lru_lock with lruvec lock 2020-12-15 14:48:04 -08:00
mprotect.c mm: don't try to NUMA-migrate COW pages that have other uses 2022-02-23 12:03:03 +01:00
mremap.c mmmremap.c: avoid pointless invalidate_range_start/end on mremap(old_size=0) 2022-04-13 20:59:22 +02:00
msync.c mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start 2021-04-30 11:20:37 -07:00
nommu.c mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling 2024-12-14 19:50:38 +01:00
oom_kill.c memcg: fix soft lockup in the OOM process 2025-03-13 12:50:48 +01:00
page-writeback.c mm: fix ratelimit_pages update error in dirty_ratio_handler() 2025-06-27 11:05:26 +01:00
page_alloc.c mm/mm_init: fix hash table order logging in alloc_large_system_hash() 2025-12-07 06:09:32 +09:00
page_counter.c mm: page_counter: mitigate consequences of a page_counter underflow 2021-04-30 11:20:38 -07:00
page_ext.c mm/migrate: add CPU hotplug to demotion #ifdef 2021-10-18 20:22:02 -10:00
page_idle.c mm/idle_page_tracking: make PG_idle reusable 2021-09-08 11:50:24 -07:00
page_io.c mm: fix unexpected zeroed page mapping with zram swap 2022-04-20 09:34:18 +02:00
page_isolation.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
page_owner.c mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE 2021-09-08 11:50:22 -07:00
page_poison.c mm: page_poison: print page info when corruption is caught 2021-04-30 11:20:36 -07:00
page_reporting.c mm/page_reporting: allow driver to specify reporting order 2021-06-29 10:53:47 -07:00
page_reporting.h mm/page_reporting: export reporting order as module parameter 2021-06-29 10:53:47 -07:00
page_vma_mapped.c mm: device exclusive memory access 2021-07-01 11:06:03 -07:00
pagewalk.c mm: pagewalk: Fix race between unmap and page walker 2022-09-08 12:28:05 +02:00
percpu-internal.h Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu 2021-07-01 17:17:24 -07:00
percpu-km.c percpu: flush tlb in pcpu_reclaim_populated() 2021-07-04 18:30:17 +00:00
percpu-stats.c percpu: rework memcg accounting 2021-06-05 20:43:15 +00:00
percpu-vm.c percpu: flush tlb in pcpu_reclaim_populated() 2021-07-04 18:30:17 +00:00
percpu.c memblock: drop memblock_free_early_nid() and memblock_free_early() 2025-03-13 12:50:07 +01:00
pgalloc-track.h mm: fix typos in comments 2021-05-07 00:26:35 -07:00
pgtable-generic.c mm/thp: fix __split_huge_pmd_locked() on shmem migration entry 2021-06-16 09:24:42 -07:00
process_vm_access.c mm/process_vm_access.c: remove duplicate include 2021-05-05 11:27:27 -07:00
ptdump.c mm/ptdump: take the memory hotplug lock inside ptdump_walk_pgd() 2025-08-28 16:24:32 +02:00
readahead.c vfs: fix readahead(2) on block devices 2023-11-20 11:08:13 +01:00
rmap.c mm/rmap: reject hugetlb folios in folio_make_device_exclusive() 2025-10-02 13:38:59 +02:00
rodata_test.c mm/rodata_test.c: fix missing function declaration 2020-08-21 09:52:53 -07:00
secretmem.c mm/secretmem: fix use-after-free race in fault handler 2025-12-07 06:09:32 +09:00
shmem.c mm: update memfd seal write check to include F_SEAL_WRITE 2025-08-28 16:24:30 +02:00
shuffle.c mm: eliminate "expecting prototype" kernel-doc warnings 2021-04-16 16:10:36 -07:00
shuffle.h mm/shuffle: fix section mismatch warning 2021-05-22 15:09:07 -10:00
slab.c slab: Introduce kmalloc_size_roundup() 2025-04-10 14:31:49 +02:00
slab.h mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-27 14:38:51 +02:00
slab_common.c mm, slab: remove duplicate kernel-doc comment for ksize() 2025-04-10 14:32:06 +02:00
slob.c slab: Introduce kmalloc_size_roundup() 2025-04-10 14:31:49 +02:00
slub.c mm/slub: avoid accessing metadata when pointer is invalid in object_err() 2025-09-09 18:50:24 +02:00
sparse-vmemmap.c mm: introduce and use {pgd,p4d}_populate_kernel() 2025-10-02 13:38:59 +02:00
sparse.c memblock: drop memblock_free_early_nid() and memblock_free_early() 2025-03-13 12:50:07 +01:00
swap.c mm: fs: invalidate bh_lrus for only cold path 2021-09-24 16:13:35 -07:00
swap_cgroup.c mm: memcontrol: make swap tracking an integral part of memory control 2020-06-03 20:09:48 -07:00
swap_slots.c mm: Replace deprecated CPU-hotplug functions. 2021-08-28 01:46:17 +02:00
swap_state.c mm: swap: get rid of livelock in swapin readahead 2022-03-23 09:16:41 +01:00
swapfile.c mm/swapfile: skip HugeTLB pages for unuse_vma 2024-10-22 15:40:41 +02:00
truncate.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
usercopy.c mm/usercopy: return 1 from hardened_usercopy __setup() handler 2022-04-08 14:24:14 +02:00
userfaultfd.c userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb 2024-03-01 13:21:43 +01:00
util.c mm: unconditionally close VMAs on error 2024-12-14 19:50:38 +01:00
vmacache.c kernel: better document the use_mm/unuse_mm API contract 2020-06-10 19:14:18 -07:00
vmalloc.c mm/vmalloc: leave lazy MMU mode on PTE mapping error 2025-08-28 16:24:03 +02:00
vmpressure.c net-memcg: Fix scope of sockmem pressure indicators 2023-09-19 12:22:33 +02:00
vmscan.c mm: add missing release barrier on PGDAT_RECLAIM_LOCKED unlock 2025-05-02 07:44:04 +02:00
vmstat.c vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event 2024-12-14 19:50:33 +01:00
workingset.c memcg: sync flush only if periodic flush is delayed 2022-04-27 14:38:57 +02:00
z3fold.c mm/z3fold: add kerneldoc fields for z3fold_pool 2021-07-01 11:06:03 -07:00
zbud.c mm/zbud: add kerneldoc fields for zbud_pool 2021-07-01 11:06:03 -07:00
zpool.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
zsmalloc.c minmax: make generic MIN() and MAX() macros available everywhere 2025-10-19 16:21:52 +02:00
zswap.c mm/zswap.c: fix two bugs in zswap_writeback_entry() 2021-06-30 20:47:31 -07:00