linux/mm
Muchun Song 5126bdeaf9 mm/ksm: fix NULL pointer dereference when KSM zero page is enabled
commit 56df70a63e upstream.

find_mergeable_vma() can return NULL.  In this case, it leads to a crash
when we access vm_mm(its offset is 0x40) later in write_protect_page.
And this case did happen on our server.  The following call trace is
captured in kernel 4.19 with the following patch applied and KSM zero
page enabled on our server.

  commit e86c59b1b1 ("mm/ksm: improve deduplication of zero pages with colouring")

So add a vma check to fix it.

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
  Oops: 0000 [#1] SMP NOPTI
  CPU: 9 PID: 510 Comm: ksmd Kdump: loaded Tainted: G OE 4.19.36.bsk.9-amd64 #4.19.36.bsk.9
  RIP: try_to_merge_one_page+0xc7/0x760
  Code: 24 58 65 48 33 34 25 28 00 00 00 89 e8 0f 85 a3 06 00 00 48 83 c4
        60 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 8b 46 08 a8 01 75 b8 <49>
        8b 44 24 40 4c 8d 7c 24 20 b9 07 00 00 00 4c 89 e6 4c 89 ff 48
  RSP: 0018:ffffadbdd9fffdb0 EFLAGS: 00010246
  RAX: ffffda83ffd4be08 RBX: ffffda83ffd4be40 RCX: 0000002c6e800000
  RDX: 0000000000000000 RSI: ffffda83ffd4be40 RDI: 0000000000000000
  RBP: ffffa11939f02ec0 R08: 0000000094e1a447 R09: 00000000abe76577
  R10: 0000000000000962 R11: 0000000000004e6a R12: 0000000000000000
  R13: ffffda83b1e06380 R14: ffffa18f31f072c0 R15: ffffda83ffd4be40
  FS: 0000000000000000(0000) GS:ffffa0da43b80000(0000) knlGS:0000000000000000
  CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000040 CR3: 0000002c77c0a003 CR4: 00000000007626e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:
    ksm_scan_thread+0x115e/0x1960
    kthread+0xf5/0x130
    ret_from_fork+0x1f/0x30

[songmuchun@bytedance.com: if the vma is out of date, just exit]
  Link: http://lkml.kernel.org/r/20200416025034.29780-1-songmuchun@bytedance.com
[akpm@linux-foundation.org: add the conventional braces, replace /** with /*]
Fixes: e86c59b1b1 ("mm/ksm: improve deduplication of zero pages with colouring")
Co-developed-by: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Cc: Markus Elfring <Markus.Elfring@web.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200416025034.29780-1-songmuchun@bytedance.com
Link: http://lkml.kernel.org/r/20200414132905.83819-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-29 16:33:15 +02:00
..
kasan
Kconfig
Kconfig.debug
Makefile
backing-dev.c memcg: fix a crash in wb_workfn when a device disappears 2020-02-11 04:35:11 -08:00
balloon_compaction.c
cleancache.c
cma.c
cma.h
cma_debug.c
compaction.c
debug.c mm/debug.c: always print flags in dump_page() 2020-03-05 16:43:51 +01:00
debug_page_ref.c
dmapool.c
early_ioremap.c
fadvise.c
failslab.c
filemap.c mm: drop mmap_sem before calling balance_dirty_pages() in write fault 2020-01-09 10:19:55 +01:00
frame_vector.c
frontswap.c
gup.c mm/gup: allow FOLL_FORCE for get_user_pages_fast() 2020-03-05 16:43:51 +01:00
gup_benchmark.c mm/gup: fix memory leak in __gup_benchmark_ioctl 2020-01-09 10:20:00 +01:00
highmem.c
hmm.c
huge_memory.c mm: fix possible PMD dirty bit lost in set_pmd_migration_entry() 2020-03-12 13:00:19 +01:00
hugetlb.c mm/hugetlb: fix a addressing exception caused by huge_pte_offset 2020-04-29 16:33:14 +02:00
hugetlb_cgroup.c mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup() 2019-11-15 18:34:00 -08:00
hwpoison-inject.c
init-mm.c mm/init-mm.c: include <linux/mman.h> for vm_committed_as_batch 2019-10-19 06:32:32 -04:00
internal.h mm: drop mmap_sem before calling balance_dirty_pages() in write fault 2020-01-09 10:19:55 +01:00
interval_tree.c
khugepaged.c mm,thp: recheck each page before collapsing file THP 2019-11-15 18:34:00 -08:00
kmemleak-test.c
kmemleak.c
ksm.c mm/ksm: fix NULL pointer dereference when KSM zero page is enabled 2020-04-29 16:33:15 +02:00
list_lru.c
maccess.c uaccess: Add non-pagefault user-space write function 2020-01-17 19:48:40 +01:00
madvise.c mm: do not allow MADV_PAGEOUT for CoW pages 2020-03-25 08:25:57 +01:00
memblock.c
memcontrol.c mm, memcg: do not high throttle allocators based on wraparound 2020-04-17 10:50:17 +02:00
memfd.c
memory-failure.c
memory.c mm: drop mmap_sem before calling balance_dirty_pages() in write fault 2020-01-09 10:19:55 +01:00
memory_hotplug.c mm, hotplug: fix page online with DEBUG_PAGEALLOC compiled but not enabled 2020-03-12 13:00:19 +01:00
mempolicy.c mm: mempolicy: require at least one nodeid for MPOL_PREFERRED 2020-04-08 09:08:47 +02:00
mempool.c
memremap.c mm/memory_hotplug: shrink zones when offlining memory 2020-01-09 10:19:56 +01:00
memtest.c
migrate.c mm: move_pages: report the number of non-attempted pages 2020-02-11 04:35:13 -08:00
mincore.c
mlock.c
mm_init.c
mmap.c mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-28 17:22:21 +01:00
mmu_context.c
mmu_gather.c mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush 2020-02-11 04:35:42 -08:00
mmu_notifier.c mm/mmu_notifiers: use the right return code for WARN_ON 2019-11-06 08:47:50 -08:00
mmzone.c
mprotect.c mm, numa: fix bad pmd by atomically check for pmd_trans_huge when marking page tables prot_numa 2020-03-12 13:00:19 +01:00
mremap.c mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-28 17:22:21 +01:00
msync.c
nommu.c x86/mm: split vmalloc_sync_all() 2020-03-25 08:25:58 +01:00
oom_kill.c mm/oom: fix pgtables units mismatch in Killed process message 2020-01-09 10:19:57 +01:00
page-writeback.c mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio() 2020-01-23 08:22:41 +01:00
page_alloc.c mm/page_alloc.c: fix uninitialized memmaps on a partially populated last section 2020-02-11 04:35:42 -08:00
page_counter.c
page_ext.c
page_idle.c
page_io.c mm/page_io.c: do not free shared swap slots 2019-11-15 18:34:00 -08:00
page_isolation.c
page_owner.c
page_poison.c
page_vma_mapped.c
pagewalk.c
percpu-internal.h
percpu-km.c
percpu-stats.c
percpu-vm.c
percpu.c
pgtable-generic.c
process_vm_access.c
readahead.c
rmap.c mm: include <linux/huge_mm.h> for is_vma_temporary_stack 2019-10-19 06:32:32 -04:00
rodata_test.c
shmem.c mm/shmem.c: thp, shmem: fix conflict of above-47bit hint address and PMD alignment 2020-01-23 08:22:39 +01:00
shuffle.c
shuffle.h
slab.c mm, debug_pagealloc: don't rely on static keys too early 2020-01-23 08:22:40 +01:00
slab.h mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly 2019-11-06 08:47:50 -08:00
slab_common.c mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid 2020-01-23 08:22:39 +01:00
slob.c
slub.c slub: improve bit diffusion for freelist ptr obfuscation 2020-04-13 10:48:07 +02:00
sparse-vmemmap.c
sparse.c mm/sparse: fix kernel crash with pfn_section_valid check 2020-04-01 11:02:03 +02:00
swap.c
swap_cgroup.c
swap_slots.c
swap_state.c
swapfile.c mm/swapfile.c: move inode_lock out of claim_swapfile 2020-04-01 11:02:02 +02:00
truncate.c mm/thp: allow dropping THP from page cache 2019-10-19 06:32:33 -04:00
usercopy.c
userfaultfd.c
util.c
vmacache.c
vmalloc.c vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29 16:33:14 +02:00
vmpressure.c
vmscan.c mm/vmscan.c: don't round up scan size for online memory cgroup 2020-02-28 17:22:20 +01:00
vmstat.c mm, vmstat: reduce zone->lock holding time by /proc/pagetypeinfo 2019-11-06 08:47:50 -08:00
workingset.c
z3fold.c
zbud.c
zpool.c
zsmalloc.c mm/zsmalloc.c: fix the migrated zspage statistics. 2020-01-09 10:19:56 +01:00
zswap.c