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Eric Biggers 0f49b0519f mm/madvise.c: fix freeing of locked page with MADV_FREE 
commit 263630e8d176d87308481ebdcd78ef9426739c6b upstream.

If madvise(..., MADV_FREE) split a transparent hugepage, it called
put_page() before unlock_page().

This was wrong because put_page() can free the page, e.g. if a
concurrent madvise(..., MADV_DONTNEED) has removed it from the memory
mapping. put_page() then rightfully complained about freeing a locked
page.

Fix this by moving the unlock_page() before put_page().

This bug was found by syzkaller, which encountered the following splat:

    BUG: Bad page state in process syzkaller412798  pfn:1bd800
    page:ffffea0006f60000 count:0 mapcount:0 mapping:          (null) index:0x20a00
    flags: 0x200000000040019(locked|uptodate|dirty|swapbacked)
    raw: 0200000000040019 0000000000000000 0000000000020a00 00000000ffffffff
    raw: ffffea0006f60020 ffffea0006f60020 0000000000000000 0000000000000000
    page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
    bad because of flags: 0x1(locked)
    Modules linked in:
    CPU: 1 PID: 3037 Comm: syzkaller412798 Not tainted 4.13.0-rc5+ #35
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Call Trace:
     __dump_stack lib/dump_stack.c:16 [inline]
     dump_stack+0x194/0x257 lib/dump_stack.c:52
     bad_page+0x230/0x2b0 mm/page_alloc.c:565
     free_pages_check_bad+0x1f0/0x2e0 mm/page_alloc.c:943
     free_pages_check mm/page_alloc.c:952 [inline]
     free_pages_prepare mm/page_alloc.c:1043 [inline]
     free_pcp_prepare mm/page_alloc.c:1068 [inline]
     free_hot_cold_page+0x8cf/0x12b0 mm/page_alloc.c:2584
     __put_single_page mm/swap.c:79 [inline]
     __put_page+0xfb/0x160 mm/swap.c:113
     put_page include/linux/mm.h:814 [inline]
     madvise_free_pte_range+0x137a/0x1ec0 mm/madvise.c:371
     walk_pmd_range mm/pagewalk.c:50 [inline]
     walk_pud_range mm/pagewalk.c:108 [inline]
     walk_p4d_range mm/pagewalk.c:134 [inline]
     walk_pgd_range mm/pagewalk.c:160 [inline]
     __walk_page_range+0xc3a/0x1450 mm/pagewalk.c:249
     walk_page_range+0x200/0x470 mm/pagewalk.c:326
     madvise_free_page_range.isra.9+0x17d/0x230 mm/madvise.c:444
     madvise_free_single_vma+0x353/0x580 mm/madvise.c:471
     madvise_dontneed_free mm/madvise.c:555 [inline]
     madvise_vma mm/madvise.c:664 [inline]
     SYSC_madvise mm/madvise.c:832 [inline]
     SyS_madvise+0x7d3/0x13c0 mm/madvise.c:760
     entry_SYSCALL_64_fastpath+0x1f/0xbe

Here is a C reproducer:

    #define _GNU_SOURCE
    #include <pthread.h>
    #include <sys/mman.h>
    #include <unistd.h>

    #define MADV_FREE	8
    #define PAGE_SIZE	4096

    static void *mapping;
    static const size_t mapping_size = 0x1000000;

    static void *madvise_thrproc(void *arg)
    {
        madvise(mapping, mapping_size, (long)arg);
    }

    int main(void)
    {
        pthread_t t[2];

        for (;;) {
            mapping = mmap(NULL, mapping_size, PROT_WRITE,
                           MAP_POPULATE|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);

            munmap(mapping + mapping_size / 2, PAGE_SIZE);

            pthread_create(&t[0], 0, madvise_thrproc, (void*)MADV_DONTNEED);
            pthread_create(&t[1], 0, madvise_thrproc, (void*)MADV_FREE);
            pthread_join(t[0], NULL);
            pthread_join(t[1], NULL);
            munmap(mapping, mapping_size);
        }
    }

Note: to see the splat, CONFIG_TRANSPARENT_HUGEPAGE=y and
CONFIG_DEBUG_VM=y are needed.

Google Bug Id: 64696096

Link: http://lkml.kernel.org/r/20170823205235.132061-1-ebiggers3@gmail.com
Fixes: 854e9ed09ded ("mm: support madvise(MADV_FREE)")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
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>
2017-08-30 10:21:47 +02:00
..
kasan
kasan: respect /proc/sys/kernel/traceoff_on_warning
2017-06-17 06:41:51 +02:00
backing-dev.c
block: fix double-free in the failure path of cgwb_bdi_init()
2017-02-26 11:10:52 +01:00
balloon_compaction.c
mm: balloon: use general non-lru movable page feature
2016-07-26 16:19:19 -07:00
bootmem.c
mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping
2016-10-11 15:06:33 -07:00
cleancache.c
cleancache: constify cleancache_ops structure
2016-01-27 09:09:57 -05:00
cma_debug.c
mm/cma_debug: correct size input to bitmap function
2015-07-17 16:39:54 -07:00
cma.c
mm/cma.c: check the max limit for cma allocation
2016-11-11 08:12:37 -08:00
cma.h
mm: cma: mark cma_bitmap_maxno() inline in header
2015-08-14 15:56:32 -07:00
compaction.c
mm, compaction: fix NR_ISOLATED_* stats for pfn based migration
2017-01-12 11:39:32 +01:00
debug_page_ref.c
mm/page_ref: add tracepoint to track down page reference manipulation
2016-03-17 15:09:34 -07:00
debug.c
mm: clarify why we avoid page_mapcount() for slab pages in dump_page()
2016-10-07 18:46:29 -07:00
dmapool.c
mm: convert printk(KERN_<LEVEL> to pr_<level>
2016-03-17 15:09:34 -07:00
early_ioremap.c
mm/early_ioremap: use offset_in_page macro
2015-11-05 19:34:48 -08:00
fadvise.c
mm/fadvise.c: do not discard partial pages with POSIX_FADV_DONTNEED
2016-06-09 14:23:11 -07:00
failslab.c
mm: fault-inject take over bootstrap kmem_cache check
2016-03-15 16:55:16 -07:00
filemap.c
mm: do not access page->mapping directly on page_endio
2017-03-12 06:41:43 +01:00
frame_vector.c
mm: replace get_vaddr_frames() write/force parameters with gup_flags
2016-10-19 08:11:24 -07:00
frontswap.c
mm, frontswap: convert frontswap_enabled to static key
2016-07-26 16:19:19 -07:00
gup.c
mm: larger stack guard gap, between vmas
2017-06-24 07:11:18 +02:00
highmem.c
mm/highmem: make nr_free_highpages() handles all highmem zones by itself
2016-05-19 19:12:14 -07:00
huge_memory.c
thp, mm: fix crash due race in MADV_FREE handling
2017-07-21 07:42:21 +02:00
hugetlb_cgroup.c
mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size
2016-05-20 17:58:30 -07:00
hugetlb.c
mm, hugetlb: use pte_present() instead of pmd_present() in follow_huge_pmd()
2017-04-08 09:30:35 +02:00
hwpoison-inject.c
hwpoison: use page_cgroup_ino for filtering by memcg
2015-09-10 13:29:01 -07:00
init-mm.c
mm: Add a user_ns owner to mm_struct and fix ptrace permission checks
2017-01-06 10:40:13 +01:00
internal.h
mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries
2017-08-11 08:49:29 -07:00
interval_tree.c
mm: replace vma->sharead.linear with vma->shared
2015-02-10 14:30:31 -08:00
Kconfig
Allow KASAN and HOTPLUG_MEMORY to co-exist when doing build testing
2016-10-27 16:23:01 -07:00
Kconfig.debug
PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO
2016-09-13 02:35:27 +02:00
khugepaged.c
mm: khugepaged: fix radix tree node leak in shmem collapse error path
2017-01-12 11:39:32 +01:00
kmemcheck.c
mm: convert printk(KERN_<LEVEL> to pr_<level>
2016-03-17 15:09:34 -07:00
kmemleak-test.c
mm: convert printk(KERN_<LEVEL> to pr_<level>
2016-03-17 15:09:34 -07:00
kmemleak.c
mm: kmemleak: scan .data.ro_after_init
2016-11-11 08:12:37 -08:00
ksm.c
ksm: prevent crash after write_protect_page fails
2017-06-07 12:07:49 +02:00
list_lru.c
mm/list_lru.c: fix list_lru_count_node() to be race free
2017-07-21 07:42:21 +02:00
maccess.c
x86: remove more uaccess_32.h complexity
2016-05-22 17:21:27 -07:00
madvise.c
mm/madvise.c: fix freeing of locked page with MADV_FREE
2017-08-30 10:21:47 +02:00
Makefile
Disable the __builtin_return_address() warning globally after all
2016-10-12 10:23:41 -07:00
memblock.c
mm: discard memblock data later
2017-08-24 17:12:19 -07:00
memcontrol.c
mm: memcontrol: use special workqueue for creating per-memcg caches
2017-04-21 09:31:23 +02:00
memory_hotplug.c
base/memory, hotplug: fix a kernel oops in show_valid_zones()
2017-02-09 08:08:28 +01:00
memory-failure.c
mm/memory-failure.c: use compound_head() flags for huge pages
2017-06-24 07:11:16 +02:00
memory.c
mm: fix double mmap_sem unlock on MMF_UNSTABLE enforced SIGBUS
2017-08-24 17:12:19 -07:00
mempolicy.c
mm/mempolicy: fix use after free when calling get_mempolicy
2017-08-24 17:12:20 -07:00
mempool.c
Revert "mm, mempool: only set __GFP_NOMEMALLOC if there are free elements"
2016-07-28 16:07:41 -07:00
memtest.c
memtest: remove unused header files
2015-09-08 15:35:28 -07:00
migrate.c
Sanitize 'move_pages()' permission checks
2017-08-24 17:12:21 -07:00
mincore.c
mm, swap: use offset of swap entry as key of swap cache
2016-10-07 18:46:28 -07:00
mlock.c
mlock: fix mlock count can not decrease in race condition
2017-06-07 12:07:49 +02:00
mm_init.c
mm: convert printk(KERN_<LEVEL> to pr_<level>
2016-03-17 15:09:34 -07:00
mmap.c
mm: fix overflow check in expand_upwards()
2017-07-21 07:42:22 +02:00
mmu_context.c
mm/mmu_context, sched/core: Fix mmu_context.h assumption
2016-04-28 11:44:19 +02:00
mmu_notifier.c
fix Christoph's email addresses
2016-03-17 15:09:34 -07:00
mmzone.c
mm, page_alloc: inline the fast path of the zonelist iterator
2016-05-19 19:12:14 -07:00
mprotect.c
mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries
2017-08-11 08:49:29 -07:00
mremap.c
mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries
2017-08-11 08:49:29 -07:00
msync.c
mm/msync: use offset_in_page macro
2015-11-05 19:34:48 -08:00
nobootmem.c
mm: discard memblock data later
2017-08-24 17:12:19 -07:00
nommu.c
ptrace: Don't allow accessing an undumpable mm
2017-01-06 10:40:13 +01:00
oom_kill.c
oom: print nodemask in the oom report
2016-10-07 18:46:29 -07:00
page_alloc.c
mm: discard memblock data later
2017-08-24 17:12:19 -07:00
page_counter.c
mm: page_counter: let page_counter_try_charge() return bool
2015-11-05 19:34:48 -08:00
page_ext.c
mm/page_ext: support extra space allocation by page_ext user
2016-10-07 18:46:27 -07:00
page_idle.c
mm, vmscan: move lru_lock to the node
2016-07-28 16:07:41 -07:00
page_io.c
mm/page_io.c: replace some BUG_ON()s with VM_BUG_ON_PAGE()
2016-10-07 18:46:29 -07:00
page_isolation.c
mm/page_isolation: fix typo: "paes" -> "pages"
2016-10-07 18:46:29 -07:00
page_owner.c
mm/page_owner: don't define fields on struct page_ext by hard-coding
2016-10-07 18:46:27 -07:00
page_poison.c
mm: check the return value of lookup_page_ext for all call sites
2016-06-03 15:06:22 -07:00
page-writeback.c
mm: don't use radix tree writeback tags for pages in swap cache
2016-10-07 18:46:28 -07:00
pagewalk.c
thp: rename split_huge_page_pmd() to split_huge_pmd()
2016-01-15 17:56:32 -08:00
percpu-km.c
mm: percpu: use pr_fmt to prefix output
2016-03-17 15:09:34 -07:00
percpu-vm.c
…
percpu.c
percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages
2017-03-26 13:05:58 +02:00
pgtable-generic.c
mm/thp/migration: switch from flush_tlb_range to flush_pmd_tlb_range
2016-03-17 15:09:34 -07:00
process_vm_access.c
mm: remove write/force parameters from __get_user_pages_unlocked()
2016-10-18 14:13:37 -07:00
quicklist.c
fix Christoph's email addresses
2016-03-17 15:09:34 -07:00
readahead.c
mm: silently skip readahead for DAX inodes
2016-08-26 17:39:35 -07:00
rmap.c
mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries
2017-08-11 08:49:29 -07:00
shmem.c
mm, shmem: fix handling /sys/kernel/mm/transparent_hugepage/shmem_enabled
2017-08-30 10:21:46 +02:00
slab_common.c
slub: move synchronize_sched out of slab_mutex on shrink
2017-03-22 12:43:38 +01:00
slab.c
slub: move synchronize_sched out of slab_mutex on shrink
2017-03-22 12:43:38 +01:00
slab.h
slub: move synchronize_sched out of slab_mutex on shrink
2017-03-22 12:43:38 +01:00
slob.c
slub: move synchronize_sched out of slab_mutex on shrink
2017-03-22 12:43:38 +01:00
slub.c
mm/slub.c: trace free objects at KERN_INFO
2017-06-07 12:07:49 +02:00
sparse-vmemmap.c
treewide: replace obsolete _refok by __ref
2016-08-02 17:31:41 -04:00
sparse.c
treewide: replace obsolete _refok by __ref
2016-08-02 17:31:41 -04:00
swap_cgroup.c
mm, swap_cgroup: reschedule when neeed in swap_cgroup_swapoff()
2017-07-05 14:40:17 +02:00
swap_state.c
mm, swap: use offset of swap entry as key of swap cache
2016-10-07 18:46:28 -07:00
swap.c
thp: reduce usage of huge zero page's atomic counter
2016-10-07 18:46:28 -07:00
swapfile.c
mm: support anonymous stable page
2017-01-19 20:17:59 +01:00
truncate.c
fs: add i_blocksize()
2017-06-14 15:06:00 +02:00
usercopy.c
mm: usercopy: Check for module addresses
2016-09-20 16:07:39 -07:00
userfaultfd.c
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
2016-04-04 10:41:08 -07:00
util.c
Merge branch 'mm-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2016-10-22 09:39:10 -07:00
vmacache.c
mm: unrig VMA cache hit ratio
2016-10-07 18:46:27 -07:00
vmalloc.c
mm/vmalloc.c: huge-vmap: fail gracefully on unexpected huge vmap mappings
2017-07-05 14:40:28 +02:00
vmpressure.c
mm: vmpressure: fix sending wrong events on underflow
2017-03-12 06:41:43 +01:00
vmscan.c
mm, vmscan: consider eligible zones in get_scan_count
2017-03-12 06:41:44 +01:00
vmstat.c
seq/proc: modify seq_put_decimal_[u]ll to take a const char *, not char
2016-10-07 18:46:30 -07:00
workingset.c
mm: workingset: fix premature shadow node shrinking with cgroups
2017-04-08 09:30:36 +02:00
z3fold.c
mm/z3fold.c: avoid modifying HEADLESS page and minor cleanup
2016-06-03 16:02:55 -07:00
zbud.c
mm/zbud.c: use list_last_entry() instead of list_tail_entry()
2016-01-15 11:40:52 -08:00
zpool.c
mm: zsmalloc: constify struct zs_pool name
2015-11-06 17:50:42 -08:00
zsmalloc.c
zsmalloc: expand class bit
2017-04-21 09:31:19 +02:00
zswap.c
zswap: disable changing params if init fails
2017-02-09 08:08:27 +01:00