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Axel Rasmussen 7ed9d238c7 userfaultfd: release page in error path to avoid BUG_ON 
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>
2021-05-14 19:41:32 -07:00
..
kasan
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
kfence
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
backing-dev.c
mm/backing-dev.c: use might_alloc()
2021-02-26 09:41:01 -08:00
balloon_compaction.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
cleancache.c
Driver Core and debugfs changes for 5.3-rc1
2019-07-12 12:24:03 -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
cma.c
mm: use proper type for cma_[alloc|release]
2021-05-05 11:27:24 -07:00
cma.h
mm: cma: support sysfs
2021-05-05 11:27:24 -07:00
compaction.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
debug_page_ref.c
…
debug_vm_pgtable.c
mm: HUGE_VMAP arch support cleanup
2021-04-30 11:20:40 -07:00
debug.c
mm/debug: improve memcg debugging
2021-02-24 13:38:27 -08:00
dmapool.c
mm/dmapool: switch from strlcpy to strscpy
2021-04-30 11:20:39 -07:00
early_ioremap.c
mm/early_ioremap.c: use __func__ instead of function name
2021-02-26 09:41:02 -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: fix typos in comments
2021-05-07 00:26:35 -07:00
frontswap.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -07:00
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
gup.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
highmem.c
mm: fix typos in comments
2021-05-07 00:26:35 -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: fix typos in comments
2021-05-07 00:26:35 -07:00
hugetlb_cgroup.c
hugetlb: make free_huge_page irq safe
2021-05-05 11:27:22 -07:00
hugetlb.c
mm/hugetlb: fix cow where page writtable in child
2021-05-14 19:41:32 -07:00
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
2020-12-15 12:13:39 -08:00
internal.h
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
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 vmap_range from mm/ioremap.c to mm/vmalloc.c
2021-04-30 11:20:40 -07:00
Kconfig
mm,memory_hotplug: allocate memmap from the added memory range
2021-05-05 11:27:26 -07:00
Kconfig.debug
mm, page_poison: remove CONFIG_PAGE_POISONING_ZERO
2020-12-15 12:13:46 -08:00
khugepaged.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
kmemleak.c
mm/kmemleak.c: fix a typo
2021-04-30 11:20:36 -07:00
ksm.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
list_lru.c
mm: vmscan: consolidate shrinker_maps handling code
2021-05-05 11:27:23 -07:00
maccess.c
uaccess: add force_uaccess_{begin,end} helpers
2020-08-12 10:57:59 -07:00
madvise.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
Makefile
mm,memory_hotplug: add kernel boot option to enable memmap_on_memory
2021-05-05 11:27:27 -07:00
mapping_dirty_helpers.c
mm/mapping_dirty_helpers: guard hugepage pud's usage
2021-04-16 16:10:37 -07:00
memblock.c
memblock: remove return value of memblock_free_all()
2021-02-22 13:01:23 -08:00
memcontrol.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
memfd.c
mm: page cache: store only head pages in i_pages
2019-09-24 15:54:08 -07:00
memory_hotplug.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -07:00
memory-failure.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
memory.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
mempolicy.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
mempool.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -07:00
memremap.c
mm/memremap.c: fix improper SPDX comment style
2021-04-30 11:20:37 -07:00
memtest.c
…
migrate.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
mincore.c
inode: make init and permission helpers idmapped mount aware
2021-01-24 14:27:16 +01:00
mlock.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -07:00
mm_init.c
include/linux/page-flags-layout.h: cleanups
2021-04-30 11:20:42 -07:00
mmap_lock.c
mm: mmap_lock: add tracepoints around lock acquisition
2020-12-15 12:13:41 -08:00
mmap.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
mmu_gather.c
mm: eliminate "expecting prototype" kernel-doc warnings
2021-04-16 16:10:36 -07:00
mmu_notifier.c
mm/mmu_notifiers: ensure range_end() is paired with range_start()
2021-03-25 09:22:55 -07:00
mmzone.c
mm/lru: replace pgdat lru_lock with lruvec lock
2020-12-15 14:48:04 -08:00
mprotect.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
mremap.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
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/vmalloc: remove vwrite()
2021-05-07 00:26:34 -07:00
oom_kill.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
page_alloc.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
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: fix some spelling mistakes in comments
2020-12-15 22:46:19 -08:00
page_idle.c
mm: page_idle_get_page() does not need lru_lock
2020-12-15 14:48:03 -08:00
page_io.c
swap: fix swapfile read/write offset
2021-03-02 17:25:46 -07:00
page_isolation.c
mm/page_isolation: do not isolate the max order page
2020-12-15 12:13:45 -08:00
page_owner.c
mm: fix typos in comments
2021-05-07 00:26:35 -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: use list_entry_is_head() in page_reporting_cycle()
2021-02-24 13:38:30 -08:00
page_reporting.h
mm: introduce include/linux/pgtable.h
2020-06-09 09:39:13 -07:00
page_vma_mapped.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
page-writeback.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
pagewalk.c
mmap locking API: convert mmap_sem comments
2020-06-09 09:39:14 -07:00
percpu-internal.h
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
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
2021-04-09 13:58:38 +00:00
percpu-vm.c
mm/vmalloc: remove unmap_kernel_range
2021-04-30 11:20:40 -07:00
percpu.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
pgalloc-track.h
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
pgtable-generic.c
mm/pgtable-generic.c: optimize the VM_BUG_ON condition in pmdp_huge_clear_flush()
2021-02-24 13:38:30 -08:00
process_vm_access.c
mm/process_vm_access.c: remove duplicate include
2021-05-05 11:27:27 -07:00
ptdump.c
mm: ptdump: fix build failure
2021-04-16 16:10:37 -07:00
readahead.c
mm: Implement readahead_control pageset expansion
2021-04-23 10:14:29 +01:00
rmap.c
mm: fix some typos and code style problems
2021-05-07 00:26:33 -07:00
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
2021-05-14 19:41:32 -07:00
shuffle.c
mm: eliminate "expecting prototype" kernel-doc warnings
2021-04-16 16:10:36 -07:00
shuffle.h
mm/shuffle: remove dynamic reconfiguration
2020-08-07 11:33:29 -07:00
slab_common.c
mm, slub: move slub_debug static key enabling outside slab_mutex
2021-05-14 19:41:32 -07:00
slab.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
slab.h
kasan, mm: integrate slab init_on_alloc with HW_TAGS
2021-04-30 11:20:41 -07:00
slob.c
mm: Don't build mm_dump_obj() on CONFIG_PRINTK=n kernels
2021-03-08 14:18:46 -08:00
slub.c
mm, slub: move slub_debug static key enabling outside slab_mutex
2021-05-14 19:41:32 -07:00
sparse-vmemmap.c
mm/sparse: only sub-section aligned range would be populated
2020-08-07 11:33:27 -07:00
sparse.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -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: fix typos in comments
2021-05-07 00:26:35 -07:00
swap_state.c
mm: fix some typos and code style problems
2021-05-07 00:26:33 -07:00
swap.c
mm: fix some typos and code style problems
2021-05-07 00:26:33 -07:00
swapfile.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -07:00
truncate.c
mm: stop accounting shadow entries
2021-05-05 11:27:19 -07:00
usercopy.c
mm/usercopy.c: delete duplicated word
2020-08-12 10:57:58 -07:00
userfaultfd.c
userfaultfd: add UFFDIO_CONTINUE ioctl
2021-05-05 11:27:22 -07:00
util.c
mm/util.c: fix typo
2021-05-05 11:27:25 -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: fix typos in comments
2021-05-07 00:26:35 -07:00
vmpressure.c
mm: vmpressure: use mem_cgroup_is_root API
2020-04-02 09:35:31 -07:00
vmscan.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -07:00
vmstat.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
workingset.c
mm: stop accounting shadow entries
2021-05-05 11:27:19 -07:00
z3fold.c
mm: fix some typos and code style problems
2021-05-07 00:26:33 -07:00
zbud.c
mm: set the sleep_mapped to true for zbud and z3fold
2021-02-26 09:41:01 -08:00
zpool.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
zsmalloc.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
zswap.c
mm/zswap.c: switch from strlcpy to strscpy
2021-05-05 11:27:27 -07:00