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Date:   Mon, 16 Apr 2018 01:42:05 +0000
From:   bugzilla-daemon@...zilla.kernel.org
To:     linux-ext4@...nel.org
Subject: [Bug 199403] New: use-after-free in ext4_ext_remove_space() when
 mounting and operating a crafted ext4 image

https://bugzilla.kernel.org/show_bug.cgi?id=199403

            Bug ID: 199403
           Summary: use-after-free in ext4_ext_remove_space() when
                    mounting and operating a crafted ext4 image
           Product: File System
           Version: 2.5
    Kernel Version: 4.16
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: ext4
          Assignee: fs_ext4@...nel-bugs.osdl.org
          Reporter: wen.xu@...ech.edu
        Regression: No

Created attachment 275387
  --> https://bugzilla.kernel.org/attachment.cgi?id=275387&action=edit
The crafted image which causes kernel panic

- Overview
use-after-free in ext4_ext_remove_space() when mounting and operating a crafted
ext4 image

- Reproduce 
I feel it has higher probability to trigger the bug using VM with 1 or 2 cores.
# mkdir mnt
# mount -t ext4 65.img mnt
# gcc -o poc poc.c
# ./poc ./mnt

I reproduce it on both ext4 dev branch and latest linux kernel branch. With
latest linux kernel branch, use-after-free is detected in
jbd2_journal_commit_transaction. 

- Kernel Dump (ext4 dev branch, 4.16.0-rc1)
[  262.536008]
==================================================================
[  262.537223] BUG: KASAN: use-after-free in ext4_ext_remove_space+0x563/0x1d40
[  262.538275] Read of size 4 at addr ffff8800691c72ac by task poc/1791

[  262.539507] CPU: 1 PID: 1791 Comm: poc Not tainted 4.16.0-rc1+ #3
[  262.539511] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
Ubuntu-1.8.2-1ubuntu1 04/01/2014
[  262.539514] Call Trace:
[  262.539536]  dump_stack+0x63/0x8d
[  262.539546]  print_address_description+0x70/0x290
[  262.539869]  kasan_report+0x290/0x390
[  262.539887]  ? ext4_ext_remove_space+0x563/0x1d40
[  262.539900]  __asan_load4+0x78/0x80
[  262.539906]  ext4_ext_remove_space+0x563/0x1d40
[  262.539913]  ? ext4_es_free_extent+0x109/0x210
[  262.539919]  ? __kasan_slab_free+0x153/0x1a0
[  262.539926]  ? kmem_cache_free+0x7c/0x1f0
[  262.539933]  ? ext4_es_free_extent+0x109/0x210
[  262.539939]  ? ext4_ext_index_trans_blocks+0x70/0x70
[  262.539946]  ? ext4_es_scan+0x1c0/0x1c0
[  262.539954]  ext4_ext_truncate+0xd2/0xe0
[  262.539962]  ext4_truncate+0x5e7/0x760
[  262.539968]  ? ext4_punch_hole+0x680/0x680
[  262.539975]  ? ext4_empty_dir+0x420/0x420
[  262.539981]  ext4_setattr+0x869/0xe00
[  262.539991]  notify_change+0x4d8/0x670
[  262.539998]  do_truncate+0xe8/0x160
[  262.540002]  ? do_truncate+0xe8/0x160
[  262.540007]  ? file_open_root+0x1c0/0x1c0
[  262.540016]  ? common_perm+0x1c0/0x1c0
[  262.540026]  path_openat+0x5fb/0x1e30
[  262.540034]  ? __save_stack_trace+0x92/0x100
[  262.540042]  ? vfs_link+0x4e0/0x4e0
[  262.540048]  ? kasan_kmalloc+0xad/0xe0
[  262.540053]  ? kmem_cache_alloc+0xbb/0x1d0
[  262.540059]  ? getname_flags+0x76/0x2c0
[  262.540064]  ? getname+0x12/0x20
[  262.540069]  ? do_sys_open+0x14b/0x2c0
[  262.540073]  ? SyS_open+0x1e/0x20
[  262.540082]  ? do_syscall_64+0xf2/0x1f0
[  262.540091]  ? entry_SYSCALL_64_after_hwframe+0x21/0x86
[  262.540097]  ? mb_free_blocks+0xa40/0xa40
[  262.540104]  ? rcu_segcblist_enqueue+0x79/0x90
[  262.540111]  ? call_rcu_sched+0x17/0x20
[  262.540118]  do_filp_open+0x12b/0x1d0
[  262.540124]  ? may_open_dev+0x50/0x50
[  262.540131]  ? kasan_kmalloc+0xad/0xe0
[  262.540138]  do_sys_open+0x17c/0x2c0
[  262.540143]  ? do_sys_open+0x17c/0x2c0
[  262.540148]  ? filp_open+0x60/0x60
[  262.540155]  ? mem_cgroup_handle_over_high+0x21/0xd0
[  262.540160]  ? do_sys_open+0x2c0/0x2c0
[  262.540165]  SyS_open+0x1e/0x20
[  262.540170]  do_syscall_64+0xf2/0x1f0
[  262.540177]  entry_SYSCALL_64_after_hwframe+0x21/0x86
[  262.540182] RIP: 0033:0x7f1c856dc040
[  262.540185] RSP: 002b:00007ffe6287d778 EFLAGS: 00000246 ORIG_RAX:
0000000000000002
[  262.540191] RAX: ffffffffffffffda RBX: 0000000000000000 RCX:
00007f1c856dc040
[  262.540194] RDX: 00000000000001ff RSI: 0000000000000202 RDI:
0000000001d6e080
[  262.540197] RBP: 00007ffe6287d8e0 R08: 0000000000000003 R09:
0000000000000000
[  262.540200] R10: 0000000000000463 R11: 0000000000000246 R12:
0000000000400c20
[  262.540203] R13: 00007ffe6287d9e0 R14: 0000000000000000 R15:
0000000000000000

[  262.540517] Allocated by task 1:
[  262.541033]  save_stack+0x46/0xd0
[  262.541039]  kasan_kmalloc+0xad/0xe0
[  262.541044]  kasan_slab_alloc+0x12/0x20
[  262.541049]  kmem_cache_alloc+0xbb/0x1d0
[  262.541054]  getname_flags+0x76/0x2c0
[  262.541060]  user_path_at_empty+0x23/0x40
[  262.541064]  vfs_statx+0xce/0x160
[  262.541068]  SYSC_newstat+0x8c/0xe0
[  262.541072]  SyS_newstat+0xe/0x10
[  262.541077]  do_syscall_64+0xf2/0x1f0
[  262.541082]  entry_SYSCALL_64_after_hwframe+0x21/0x86

[  262.541332] Freed by task 1:
[  262.541793]  save_stack+0x46/0xd0
[  262.541799]  __kasan_slab_free+0x13e/0x1a0
[  262.541803]  kasan_slab_free+0xe/0x10
[  262.541808]  kmem_cache_free+0x7c/0x1f0
[  262.541813]  putname+0x80/0x90
[  262.541818]  filename_lookup+0x191/0x280
[  262.541824]  user_path_at_empty+0x36/0x40
[  262.541827]  vfs_statx+0xce/0x160
[  262.541831]  SYSC_newstat+0x8c/0xe0
[  262.541835]  SyS_newstat+0xe/0x10
[  262.541840]  do_syscall_64+0xf2/0x1f0
[  262.541845]  entry_SYSCALL_64_after_hwframe+0x21/0x86

[  262.542098] The buggy address belongs to the object at ffff8800691c6600
                which belongs to the cache names_cache of size 4096
[  262.544011] The buggy address is located 3244 bytes inside of
                4096-byte region [ffff8800691c6600, ffff8800691c7600)
[  262.545840] The buggy address belongs to the page:
[  262.546585] page:ffffea0001a47000 count:1 mapcount:0 mapping:         
(null) index:0x0 compound_mapcount: 0
[  262.548082] flags: 0x1ffff0000008100(slab|head)
[  262.548808] raw: 01ffff0000008100 0000000000000000 0000000000000000
0000000100070007
[  262.550017] raw: dead000000000100 dead000000000200 ffff88006ce261c0
0000000000000000
[  262.551212] page dumped because: kasan: bad access detected

[  262.552329] Memory state around the buggy address:
[  262.553098]  ffff8800691c7180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
fb
[  262.554213]  ffff8800691c7200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
fb
[  262.555328] >ffff8800691c7280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
fb
[  262.556450]                                   ^
[  262.557161]  ffff8800691c7300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
fb
[  262.558283]  ffff8800691c7380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
fb
[  262.559402]
==================================================================
[  262.560528] Disabling lock debugging due to kernel taint
[  262.562799] EXT4-fs error (device loop0): ext4_free_blocks:4750: comm poc:
Freeing blocks not in datazone - block = 281473316796022, count = 2048
[  262.599249] EXT4-fs error (device loop0): ext4_free_blocks:4750: comm poc:
Freeing blocks not in datazone - block = 172790829285375, count = 19214
[  262.627928] EXT4-fs error (device loop0): ext4_free_blocks:4750: comm poc:
Freeing blocks not in datazone - block = 281472445215392, count = 2048
[  262.660030] EXT4-fs error (device loop0): ext4_free_blocks:4750: comm poc:
Freeing blocks not in datazone - block = 109684874774528, count = 14080
[  262.688922] ------------[ cut here ]------------
[  262.688932] kernel BUG at fs/buffer.c:3058!
[  262.689627] invalid opcode: 0000 [#1] SMP KASAN PTI
[  262.690387] Modules linked in: snd_hda_codec_generic snd_hda_intel
snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer snd soundcore mac_hid
i2c_piix4 ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi
scsi_transport_iscsi autofs4 btrfs zstd_decompress zstd_compress xxhash raid10
raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq
raid1 raid0 multipath linear 8139too crct10dif_pclmul crc32_pclmul qxl
drm_kms_helper syscopyarea sysfillrect aesni_intel sysimgblt fb_sys_fops ttm
drm aes_x86_64 crypto_simd 8139cp cryptd glue_helper mii floppy pata_acpi
[  262.698496] CPU: 0 PID: 1791 Comm: poc Tainted: G    B           
4.16.0-rc1+ #3
[  262.699642] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
Ubuntu-1.8.2-1ubuntu1 04/01/2014
[  262.701111] RIP: 0010:submit_bh_wbc+0x2c2/0x2f0
[  262.701818] RSP: 0018:ffff88006969f6a8 EFLAGS: 00010246
[  262.702632] RAX: 0000000000000004 RBX: ffff8800649e1e70 RCX:
ffffffff9d40aa2d
[  262.703728] RDX: dffffc0000000000 RSI: 0000000000000000 RDI:
ffff8800649e1e70
[  262.704837] RBP: ffff88006969f6f0 R08: 0000000000000000 R09:
ffff88006477baa8
[  262.705940] R10: 00000000eaef9492 R11: ffffed000d2d3e0b R12:
ffff88006969f7f8
[  262.707043] R13: 0000000000000000 R14: 0000000000000000 R15:
0000000000000000
[  262.708144] FS:  00007f1c85bca700(0000) GS:ffff88006d000000(0000)
knlGS:0000000000000000
[  262.709398] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  262.710290] CR2: 00007ff5c401d0d8 CR3: 000000006a948000 CR4:
00000000000006f0
[  262.711395] Call Trace:
[  262.711792]  ll_rw_block+0x9b/0xe0
[  262.712338]  __block_write_begin_int+0x7f8/0x940
[  262.713075]  ? _ext4_get_block+0x290/0x290
[  262.713726]  ? __breadahead+0xd0/0xd0
[  262.714318]  ? jbd2__journal_start+0x19d/0x300
[  262.715028]  __block_write_begin+0x11/0x20
[  262.715677]  ext4_write_begin+0x334/0x780
[  262.716313]  ? ext4_truncate+0x760/0x760
[  262.716945]  ? update_stack_state+0x27c/0x3e0
[  262.717637]  generic_perform_write+0x192/0x310
[  262.718339]  ? generic_write_checks+0x1f0/0x1f0
[  262.719053]  ? file_update_time+0x1e9/0x240
[  262.719715]  ? current_time+0x80/0x80
[  262.720300]  ? is_bpf_text_address+0xe/0x20
[  262.720974]  __generic_file_write_iter+0x261/0x2e0
[  262.721735]  ext4_file_write_iter+0x1dd/0x7e0
[  262.722426]  ? ext4_file_mmap+0x150/0x150
[  262.723067]  ? save_stack+0x46/0xd0
[  262.723628]  ? __kasan_slab_free+0x13e/0x1a0
[  262.724303]  ? kasan_slab_free+0xe/0x10
[  262.724927]  ? kmem_cache_free+0x7c/0x1f0
[  262.725571]  ? aa_file_perm+0xdb/0x570
[  262.726172]  ? SyS_open+0x1e/0x20
[  262.726710]  ? do_syscall_64+0xf2/0x1f0
[  262.727323]  ? entry_SYSCALL_64_after_hwframe+0x21/0x86
[  262.728152]  ? aa_path_link+0x210/0x210
[  262.728775]  ? iov_iter_init+0x82/0xc0
[  262.729376]  __vfs_write+0x294/0x3f0
[  262.729950]  ? kernel_read+0xa0/0xa0
[  262.730523]  ? may_open_dev+0x50/0x50
[  262.731109]  ? common_file_perm+0xca/0x220
[  262.731763]  ? rw_verify_area+0x78/0x140
[  262.732401]  vfs_write+0xf9/0x260
[  262.732939]  SyS_write+0xb4/0x140
[  262.733474]  ? SyS_read+0x140/0x140
[  262.734035]  ? SyS_read+0x140/0x140
[  262.734596]  do_syscall_64+0xf2/0x1f0
[  262.735189]  entry_SYSCALL_64_after_hwframe+0x21/0x86
[  262.735987] RIP: 0033:0x7f1c856dc2c0
[  262.736562] RSP: 002b:00007ffe6287d778 EFLAGS: 00000246 ORIG_RAX:
0000000000000001
[  262.737740] RAX: ffffffffffffffda RBX: 0000000000000000 RCX:
00007f1c856dc2c0
[  262.738849] RDX: 0000000000008000 RSI: 0000000000602140 RDI:
0000000000000003
[  262.739962] RBP: 00007ffe6287d8e0 R08: 0000000000000003 R09:
0000000000000000
[  262.741078] R10: 0000000000000463 R11: 0000000000000246 R12:
0000000000400c20
[  262.742176] R13: 00007ffe6287d9e0 R14: 0000000000000000 R15:
0000000000000000
[  262.743284] Code: 0f 45 e8 45 09 f5 e8 ee 38 f6 ff 45 89 6c 24 10 4c 89 e7
e8 b1 cd 3a 00 48 83 c4 20 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b <0f> 0b
48 8d 43 20 48 89 45 d0 48 8d 43 10 48 89 45 b8 e9 44 fe
[  262.746250] RIP: submit_bh_wbc+0x2c2/0x2f0 RSP: ffff88006969f6a8
[  262.747236] ---[ end trace c4bccbf286b60fa8 ]---

Reported by Wen Xu at SSLab, Gatech

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