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Axel Rasmussen 140cfd9980 userfaultfd: release page in error path to avoid BUG_ON 
commit 7ed9d238c7dbb1fdb63ad96a6184985151b0171c upstream.

Consider the following sequence of events:

1. Userspace issues a UFFD ioctl, which ends up calling into
   shmem_mfill_atomic_pte(). We successfully account the blocks, we
   shmem_alloc_page(), but then the copy_from_user() fails. We return
   -ENOENT. We don't release the page we allocated.
2. Our caller detects this error code, tries the copy_from_user() after
   dropping the mmap_lock, and retries, calling back into
   shmem_mfill_atomic_pte().
3. Meanwhile, let's say another process filled up the tmpfs being used.
4. So shmem_mfill_atomic_pte() fails to account blocks this time, and
   immediately returns - without releasing the page.

This triggers a BUG_ON in our caller, which asserts that the page
should always be consumed, unless -ENOENT is returned.

To fix this, detect if we have such a "dangling" page when accounting
fails, and if so, release it before returning.

Link: https://lkml.kernel.org/r/20210428230858.348400-1-axelrasmussen@google.com
Fixes: cb658a453b93 ("userfaultfd: shmem: avoid leaking blocks and used blocks in UFFDIO_COPY")
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reported-by: Hugh Dickins <hughd@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-19 10:13:11 +02:00
..
kasan
kasan: fix incorrect arguments passing in kasan_add_zero_shadow
2021-01-27 11:55:23 +01:00
backing-dev.c
bdi: replace BDI_CAP_NO_{WRITEBACK,ACCT_DIRTY} with a single flag
2020-09-24 13:43:39 -06:00
balloon_compaction.c
mm/balloon_compaction: suppress allocation warnings
2019-09-04 07:42:01 -04:00
cleancache.c
…
cma_debug.c
debugfs: make sure we can remove u32_array files cleanly
2020-07-10 13:54:00 -07:00
cma.c
cma: don't quit at first error when activating reserved areas
2020-08-12 10:57:57 -07:00
cma.h
mm: cma: use CMA_MAX_NAME to define the length of cma name array
2020-09-01 09:19:43 +02:00
compaction.c
mm, compaction: make fast_isolate_freepages() stay within zone
2021-03-04 11:38:38 +01:00
debug_page_ref.c
…
debug_vm_pgtable.c
mm/debug_vm_pgtable: avoid doing memory allocation with pgtable_t mapped.
2020-10-16 11:11:14 -07:00
debug.c
mm, dump_page: rename head_mapcount() --> head_compound_mapcount()
2020-10-13 18:38:29 -07:00
dmapool.c
mm/dmapool.c: replace hard coded function name with __func__
2020-10-13 18:38:32 -07:00
early_ioremap.c
mm/early_ioremap.c: use %pa to print resource_size_t variables
2020-01-31 10:30:38 -08:00
fadvise.c
mm, fadvise: improve the expensive remote LRU cache draining after FADV_DONTNEED
2020-10-13 18:38:29 -07:00
failslab.c
…
filemap.c
mm/filemap: add missing mem_cgroup_uncharge() to __add_to_page_cache_locked()
2021-02-10 09:29:21 +01:00
frame_vector.c
mmap locking API: convert mmap_sem comments
2020-06-09 09:39:14 -07:00
frontswap.c
mm/frontswap: mark various intentional data races
2020-08-14 19:56:56 -07:00
gup_benchmark.c
mm/gup_benchmark: take the mmap lock around GUP
2020-10-18 09:27:09 -07:00
gup.c
mm/gup: check for isolation errors
2021-05-19 10:13:08 +02:00
highmem.c
mm/highmem.c: clean up endif comments
2020-10-16 11:11:18 -07:00
hmm.c
mm: do page fault accounting in handle_mm_fault
2020-08-12 10:58:02 -07:00
huge_memory.c
mm/memcg: rename mem_cgroup_split_huge_fixup to split_page_memcg and add nr_pages argument
2021-03-30 14:31:47 +02:00
hugetlb_cgroup.c
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings
2021-03-30 14:31:54 +02:00
hugetlb.c
mm/hugeltb: handle the error case in hugetlb_fix_reserve_counts()
2021-05-19 10:13:07 +02:00
hwpoison-inject.c
mm,hwpoison-inject: don't pin for hwpoison_filter
2020-10-16 11:11:16 -07:00
init-mm.c
mm/gup: prevent gup_fast from racing with COW during fork
2020-12-30 11:53:54 +01:00
internal.h
mm: rename page_order() to buddy_order()
2020-10-16 11:11:19 -07:00
interval_tree.c
…
ioremap.c
mm: move p?d_alloc_track to separate header file
2020-08-07 11:33:26 -07:00
Kconfig
mm/zsmalloc.c: drop ZSMALLOC_PGTABLE_MAPPING
2020-12-06 10:19:07 -08:00
Kconfig.debug
treewide: replace '---help---' in Kconfig files with 'help'
2020-06-14 01:57:21 +09:00
khugepaged.c
khugepaged: fix wrong result value for trace_mm_collapse_huge_page_isolate()
2021-05-19 10:13:07 +02:00
kmemleak.c
mm/kmemleak: rely on rcu for task stack scanning
2020-10-13 18:38:27 -07:00
ksm.c
ksm: fix potential missing rmap_item for stable_node
2021-05-19 10:13:07 +02:00
list_lru.c
mm: list_lru: set shrinker map bit when child nr_items is not zero
2020-12-06 10:19:07 -08:00
maccess.c
uaccess: add force_uaccess_{begin,end} helpers
2020-08-12 10:57:59 -07:00
madvise.c
mm/madvise: replace ptrace attach requirement for process_madvise
2021-03-17 17:06:37 +01:00
Makefile
mm,kmemleak-test.c: move kmemleak-test.c to samples dir
2020-10-13 18:38:27 -07:00
mapping_dirty_helpers.c
mm/mapping_dirty_helpers: update huge page-table entry callbacks
2020-04-02 09:35:29 -07:00
memblock.c
memblock: do not start bottom-up allocations with kernel_end
2021-02-10 09:29:15 +01:00
memcontrol.c
mm: memcontrol: slab: fix obtain a reference to a freeing memcg
2021-05-14 09:50:45 +02:00
memfd.c
mm: page cache: store only head pages in i_pages
2019-09-24 15:54:08 -07:00
memory_hotplug.c
arm64: mte: Map hotplugged memory as Normal Tagged
2021-03-17 17:06:28 +01:00
memory-failure.c
mm/memory-failure: unnecessary amount of unmapping
2021-05-14 09:50:45 +02:00
memory.c
mm: fix race by making init_zero_pfn() early_initcall
2021-04-07 15:00:10 +02:00
mempolicy.c
mm: mempolicy: fix potential pte_unmap_unlock pte error
2020-11-02 12:14:19 -08:00
mempool.c
mm/mempool: add 'else' to split mutually exclusive case
2020-10-13 18:38:34 -07:00
memremap.c
mm: fix memory_failure() handling of dax-namespace metadata
2021-03-04 11:38:21 +01:00
memtest.c
…
migrate.c
mm/migrate.c: fix potential indeterminate pte entry in migrate_vma_insert_page()
2021-05-19 10:13:07 +02:00
mincore.c
mm: factor find_get_incore_page out of mincore_page
2020-10-13 18:38:29 -07:00
mlock.c
mlock: fix unevictable_pgs event counts on THP
2020-09-19 13:13:38 -07:00
mm_init.c
mm: adjust vm_committed_as_batch according to vm overcommit policy
2020-08-07 11:33:26 -07:00
mmap.c
mm/mmap.c: fix mmap return value when vma is merged after call_mmap()
2020-12-06 10:19:07 -08:00
mmu_gather.c
mmap locking API: convert mmap_sem comments
2020-06-09 09:39:14 -07:00
mmu_notifier.c
mm/mmu_notifiers: ensure range_end() is paired with range_start()
2021-03-30 14:32:06 +02:00
mmzone.c
…
mprotect.c
mm: Introduce arch_validate_flags()
2020-09-04 12:46:07 +01:00
mremap.c
mm/mremap: start addresses are properly aligned
2020-08-07 11:33:27 -07:00
msync.c
mmap locking API: use coccinelle to convert mmap_sem rwsem call sites
2020-06-09 09:39:14 -07:00
nommu.c
mm: remove alloc_vm_area
2020-10-18 09:27:10 -07:00
oom_kill.c
mm, oom_adj: don't loop through tasks in __set_oom_adj when not necessary
2020-10-13 18:38:35 -07:00
page_alloc.c
mm/memcg: set memcg when splitting page
2021-03-30 14:31:47 +02:00
page_counter.c
mm/page_counter: correct the obsolete func name in the comment of page_counter_try_charge()
2020-10-13 18:38:30 -07:00
page_ext.c
mm/page_ext.c: drop pfn_present() check when onlining
2020-04-07 10:43:40 -07:00
page_idle.c
mm/page_idle.c: skip offline pages
2020-06-08 11:05:55 -07:00
page_io.c
swap: fix swapfile read/write offset
2021-03-07 12:34:15 +01:00
page_isolation.c
mm: rename page_order() to buddy_order()
2020-10-16 11:11:19 -07:00
page_owner.c
mm: rename page_order() to buddy_order()
2020-10-16 11:11:19 -07:00
page_poison.c
mm/page_poison.c: replace bool variable with static key
2020-10-16 11:11:17 -07:00
page_reporting.c
mm: rename page_order() to buddy_order()
2020-10-16 11:11:19 -07:00
page_reporting.h
mm: introduce include/linux/pgtable.h
2020-06-09 09:39:13 -07:00
page_vma_mapped.c
mm: replace hpage_nr_pages with thp_nr_pages
2020-08-14 19:56:56 -07:00
page-writeback.c
mm: make wait_on_page_writeback() wait for multiple pending writebacks
2021-01-12 20:18:22 +01:00
pagewalk.c
mmap locking API: convert mmap_sem comments
2020-06-09 09:39:14 -07:00
percpu-internal.h
percpu: make pcpu_nr_empty_pop_pages per chunk type
2021-04-14 08:42:03 +02:00
percpu-km.c
mm: memcg/percpu: account percpu memory to memory cgroups
2020-08-12 10:57:55 -07:00
percpu-stats.c
percpu: make pcpu_nr_empty_pop_pages per chunk type
2021-04-14 08:42:03 +02:00
percpu-vm.c
mm: memcg/percpu: account percpu memory to memory cgroups
2020-08-12 10:57:55 -07:00
percpu.c
percpu: make pcpu_nr_empty_pop_pages per chunk type
2021-04-14 08:42:03 +02:00
pgalloc-track.h
mm: move p?d_alloc_track to separate header file
2020-08-07 11:33:26 -07:00
pgtable-generic.c
mm: introduce include/linux/pgtable.h
2020-06-09 09:39:13 -07:00
process_vm_access.c
mm/process_vm_access.c: include compat.h
2021-01-19 18:27:21 +01:00
ptdump.c
mm: ptdump: fix build failure
2021-04-21 13:00:57 +02:00
readahead.c
mm: use limited read-ahead to satisfy read
2020-10-17 13:49:08 -06:00
rmap.c
mm/rmap: always do TTU_IGNORE_ACCESS
2020-12-30 11:53:55 +01:00
rodata_test.c
mm/rodata_test.c: fix missing function declaration
2020-08-21 09:52:53 -07:00
shmem.c
userfaultfd: release page in error path to avoid BUG_ON
2021-05-19 10:13:11 +02:00
shuffle.c
mm: rename page_order() to buddy_order()
2020-10-16 11:11:19 -07:00
shuffle.h
mm/shuffle: remove dynamic reconfiguration
2020-08-07 11:33:29 -07:00
slab_common.c
mm/sl?b.c: remove ctor argument from kmem_cache_flags
2021-05-14 09:50:45 +02:00
slab.c
mm/sl?b.c: remove ctor argument from kmem_cache_flags
2021-05-14 09:50:45 +02:00
slab.h
mm/sl?b.c: remove ctor argument from kmem_cache_flags
2021-05-14 09:50:45 +02:00
slob.c
mm: memcg: convert vmstat slab counters to bytes
2020-08-07 11:33:24 -07:00
slub.c
mm/sl?b.c: remove ctor argument from kmem_cache_flags
2021-05-14 09:50:45 +02:00
sparse-vmemmap.c
mm/sparse: only sub-section aligned range would be populated
2020-08-07 11:33:27 -07:00
sparse.c
mm/sparse: add the missing sparse_buffer_fini() in error branch
2021-05-14 09:50:45 +02:00
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/swap_slots.c: remove always zero and unused return value of enable_swap_slots_cache()
2020-10-13 18:38:30 -07:00
swap_state.c
mm: fix some broken comments
2020-10-16 11:11:19 -07:00
swap.c
mm: move call to compound_head() in release_pages()
2020-10-13 18:38:33 -07:00
swapfile.c
swap: fix swapfile read/write offset
2021-03-07 12:34:15 +01:00
truncate.c
mm/truncate.c: make __invalidate_mapping_pages() static
2020-11-02 12:14:19 -08:00
usercopy.c
mm/usercopy.c: delete duplicated word
2020-08-12 10:57:58 -07:00
userfaultfd.c
mm/vmscan: protect the workingset on anonymous LRU
2020-08-12 10:57:55 -07:00
util.c
mm/util.c: update the kerneldoc for kstrdup_const()
2020-10-16 11:11:17 -07:00
vmacache.c
kernel: better document the use_mm/unuse_mm API contract
2020-06-10 19:14:18 -07:00
vmalloc.c
mm/vmalloc.c: fix potential memory leak
2021-01-19 18:27:21 +01:00
vmpressure.c
mm: vmpressure: use mem_cgroup_is_root API
2020-04-02 09:35:31 -07:00
vmscan.c
mm/vmscan: restore zone_reclaim_mode ABI
2021-03-04 11:38:38 +01:00
vmstat.c
mm/vmstat.c: use helper macro abs()
2020-10-16 11:11:17 -07:00
workingset.c
XArray updates for 5.9
2020-10-20 14:39:37 -07:00
z3fold.c
z3fold: prevent reclaim/free race for headless pages
2021-03-30 14:31:54 +02:00
zbud.c
mm/zbud: remove redundant initialization
2020-10-13 18:38:34 -07:00
zpool.c
mm/zpool.c: delete duplicated word and fix grammar
2020-08-12 10:57:58 -07:00
zsmalloc.c
zsmalloc: account the number of compacted pages correctly
2021-03-07 12:34:15 +01:00
zswap.c
mm/zswap: allow setting default status, compressor and allocator in Kconfig
2020-04-07 10:43:41 -07:00