Re: KASAN: slab-out-of-bounds Write in __xfrm_policy_unlink

[Dmitry Vyukov <dvyukov@google.com>]

On Sat, Nov 10, 2018 at 5:55 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> On Sat, Nov 10, 2018 at 5:54 PM, syzbot
> <syzbot+1a5442803e5354a25766@syzkaller.appspotmail.com> wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit:    29e12207174a sfc: use the new __netdev_tx_sent_queue BQL o..
>> git tree:       net-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=133c2c5d400000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=8f559fee2fc3375a
>> dashboard link: https://syzkaller.appspot.com/bug?extid=1a5442803e5354a25766
>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+1a5442803e5354a25766@syzkaller.appspotmail.com
>
> May be related to "KASAN: slab-out-of-bounds Write in __xfrm_policy_unlink"
> https://syzkaller.appspot.com/bug?extid=aa77660edbf949365033

Obviously related to itself :)
I meant "KASAN: use-after-free Write in __xfrm_policy_unlink"
https://syzkaller.appspot.com/bug?id=ebeba334a8a886e3d5dc25641e201e894d4d9657


>> ==================================================================
>> BUG: KASAN: slab-out-of-bounds in __write_once_size
>> include/linux/compiler.h:209 [inline]
>> BUG: KASAN: slab-out-of-bounds in __hlist_del include/linux/list.h:702
>> [inline]
>> BUG: KASAN: slab-out-of-bounds in hlist_del_rcu include/linux/rculist.h:455
>> [inline]
>> BUG: KASAN: slab-out-of-bounds in __xfrm_policy_unlink+0x75f/0x810
>> net/xfrm/xfrm_policy.c:1241
>> Write of size 8 at addr ffff8801b979db48 by task blkid/15614
>>
>> CPU: 1 PID: 15614 Comm: blkid Not tainted 4.20.0-rc1+ #287
>> kernel msg: ebtables bug: please report to author: Nentries wrong
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Call Trace:
>>  <IRQ>
>>  __dump_stack lib/dump_stack.c:77 [inline]
>>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>>  print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
>>  kasan_report_error mm/kasan/report.c:354 [inline]
>>  kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
>>  __asan_report_store8_noabort+0x17/0x20 mm/kasan/report.c:438
>>  __write_once_size include/linux/compiler.h:209 [inline]
>>  __hlist_del include/linux/list.h:702 [inline]
>>  hlist_del_rcu include/linux/rculist.h:455 [inline]
>>  __xfrm_policy_unlink+0x75f/0x810 net/xfrm/xfrm_policy.c:1241
>>  xfrm_policy_delete+0x49/0x90 net/xfrm/xfrm_policy.c:1266
>>  xfrm_policy_timer+0x46f/0x660 net/xfrm/xfrm_policy.c:254
>>  call_timer_fn+0x272/0x920 kernel/time/timer.c:1326
>>  expire_timers kernel/time/timer.c:1363 [inline]
>>  __run_timers+0x7e5/0xc70 kernel/time/timer.c:1682
>>  run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1695
>>  __do_softirq+0x308/0xb7e kernel/softirq.c:292
>>  invoke_softirq kernel/softirq.c:373 [inline]
>>  irq_exit+0x17f/0x1c0 kernel/softirq.c:413
>>  exiting_irq arch/x86/include/asm/apic.h:536 [inline]
>>  smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061
>>  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:804
>>  </IRQ>
>> RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:761
>> [inline]
>> RIP: 0010:count_memcg_events include/linux/memcontrol.h:742 [inline]
>> RIP: 0010:count_memcg_event_mm include/linux/memcontrol.h:763 [inline]
>> RIP: 0010:handle_mm_fault+0x9a8/0xc70 mm/memory.c:3906
>> Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 4e 02 00 00 48 83 3d 78 5b
>> 9e 07 00 0f 84 70 01 00 00 e8 7d ea cb ff 4c 89 ff 57 9d <0f> 1f 44 00 00 e9
>> 22 fa ff ff e8 69 ea cb ff 49 8d bd 20 04 00 00
>> RSP: 0000:ffff8801bbcffcc8 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
>> RAX: ffff8801bc1ae540 RBX: ffff8801c6f5dca0 RCX: 1ffff10037835dbc
>> RDX: 0000000000000000 RSI: ffffffff81b3a043 RDI: 0000000000000293
>> RBP: ffff8801bbcffd68 R08: ffff8801bc1aede0 R09: 0000000000000007
>> R10: 0000000000000000 R11: ffff8801bc1ae540 R12: 1ffff1003779ff9c
>> R13: 0000000000000200 R14: 0000000000000054 R15: 0000000000000293
>>  do_user_addr_fault arch/x86/mm/fault.c:1423 [inline]
>>  __do_page_fault+0x5e8/0xe60 arch/x86/mm/fault.c:1489
>>  do_page_fault+0xf2/0x7e0 arch/x86/mm/fault.c:1520
>>  page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1139
>> RIP: 0033:0x7f05c5e50d61
>> Code: 00 c3 f7 05 9d c4 30 00 04 00 00 00 74 07 48 8d 05 84 95 0b 00 c3 0f
>> 1f 00 48 31 c0 89 f9 83 e1 3f 66 0f ef c0 83 f9 30 77 19 <f3> 0f 6f 0f 66 0f
>> 74 c1 66 0f d7 d0 85 d2 75 7a 48 89 f8 48 83 e0
>> RSP: 002b:00007ffc5d3e2558 EFLAGS: 00010287
>> RAX: 0000000000000000 RBX: 00007f05c638487c RCX: 0000000000000020
>> RDX: 0000000000000005 RSI: 00007ffc5d3e2d48 RDI: 00007f05c6179a20
>> RBP: 00007ffc5d3e2f2b R08: 0000000000000008 R09: 0101010101010101
>> R10: 0000000000000000 R11: 00007f05c5e07060 R12: 0000000000403738
>> R13: 0000000000000001 R14: 0000000000000000 R15: 00007f05c6179a20
>>
>> Allocated by task 7136:
>>  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>>  set_track mm/kasan/kasan.c:460 [inline]
>>  kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
>>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
>>  kmem_cache_alloc+0x12e/0x730 mm/slab.c:3554
>>  mempool_alloc_slab+0x44/0x60 mm/mempool.c:505
>>  mempool_alloc+0x193/0x4a0 mm/mempool.c:385
>>  bvec_alloc+0x12a/0x2d0 block/bio.c:218
>>  bio_alloc_bioset+0x47a/0x700 block/bio.c:509
>>  bio_alloc include/linux/bio.h:393 [inline]
>>  io_submit_init_bio fs/ext4/page-io.c:374 [inline]
>>  io_submit_add_bh fs/ext4/page-io.c:399 [inline]
>>  ext4_bio_write_page+0x1304/0x1bd1 fs/ext4/page-io.c:506
>>  mpage_submit_page+0x15e/0x270 fs/ext4/inode.c:2237
>>  mpage_process_page_bufs+0x50a/0x600 fs/ext4/inode.c:2348
>>  mpage_prepare_extent_to_map+0xea5/0x19c0 fs/ext4/inode.c:2710
>>  ext4_writepages+0x140c/0x41a0 fs/ext4/inode.c:2837
>>  do_writepages+0x9a/0x1a0 mm/page-writeback.c:2328
>>  __writeback_single_inode+0x20a/0x1660 fs/fs-writeback.c:1316
>>  writeback_sb_inodes+0x71f/0x1210 fs/fs-writeback.c:1580
>>  __writeback_inodes_wb+0x1b9/0x340 fs/fs-writeback.c:1649
>>  wb_writeback+0xa73/0xfc0 fs/fs-writeback.c:1758
>>  wb_check_start_all fs/fs-writeback.c:1882 [inline]
>>  wb_do_writeback fs/fs-writeback.c:1908 [inline]
>>  wb_workfn+0xee9/0x1790 fs/fs-writeback.c:1942
>>  process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
>>  worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
>>  kthread+0x35a/0x440 kernel/kthread.c:246
>>  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
>>
>> Freed by task 5729:
>>  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>>  set_track mm/kasan/kasan.c:460 [inline]
>>  __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
>>  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
>>  __cache_free mm/slab.c:3498 [inline]
>>  kmem_cache_free+0x83/0x290 mm/slab.c:3760
>>  mempool_free_slab+0x1d/0x30 mm/mempool.c:512
>>  mempool_free+0xed/0x370 mm/mempool.c:494
>>  bvec_free+0xa8/0xd0 block/bio.c:173
>>  bio_free+0xc1/0x150 block/bio.c:259
>>  bio_put+0x187/0x200 block/bio.c:561
>>  ext4_end_bio+0x197/0x6e0 fs/ext4/page-io.c:343
>>  bio_endio+0x5d2/0xb80 block/bio.c:1773
>>  req_bio_endio block/blk-core.c:278 [inline]
>>  blk_update_request+0x585/0xd20 block/blk-core.c:3076
>>  scsi_end_request+0xde/0x860 drivers/scsi/scsi_lib.c:673
>>  scsi_io_completion+0x2ce/0x1ca0 drivers/scsi/scsi_lib.c:1093
>>  scsi_finish_command+0x579/0x970 drivers/scsi/scsi.c:248
>>  scsi_softirq_done+0x465/0x520 drivers/scsi/scsi_lib.c:1737
>>  blk_done_softirq+0x4c2/0x760 block/blk-softirq.c:37
>>  __do_softirq+0x308/0xb7e kernel/softirq.c:292
>>
>> The buggy address belongs to the object at ffff8801b979ddc0
>>  which belongs to the cache biovec-max of size 8192
>> The buggy address is located 632 bytes to the left of
>>  8192-byte region [ffff8801b979ddc0, ffff8801b979fdc0)
>> The buggy address belongs to the page:
>> page:ffffea0006e5e700 count:1 mapcount:0 mapping:ffff8801d79b6980 index:0x0
>> compound_mapcount: 0
>> flags: 0x2fffc0000010200(slab|head)
>> raw: 02fffc0000010200 ffffea000730ee08 ffffea000652d508 ffff8801d79b6980
>> raw: 0000000000000000 ffff8801b979ddc0 0000000100000001 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>>  ffff8801b979da00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>  ffff8801b979da80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>>
>>> ffff8801b979db00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>
>>                                               ^
>>  ffff8801b979db80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>  ffff8801b979dc00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>> ==================================================================
>>
>>
>> ---
>> This bug is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@googlegroups.com.
>>
>> syzbot will keep track of this bug report. See:
>> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
>> syzbot.
>>
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