btrfs-progs/check
Qu Wenruo 3dcce48fd7 btrfs-progs: check/original: Do extra verification on file extent item
[BUG]
For certain fuzzed image, `btrfs check` will fail with the following
call trace:

  Checking filesystem on issue_213.raw
  UUID: 99e50868-0bda-4d89-b0e4-7e8560312ef9
  [1/7] checking root items
  [2/7] checking extents
  Program received signal SIGABRT, Aborted.
  0x00007ffff7c88f25 in raise () from /usr/lib/libc.so.6
  (gdb) bt
  #0  0x00007ffff7c88f25 in raise () from /usr/lib/libc.so.6
  #1  0x00007ffff7c72897 in abort () from /usr/lib/libc.so.6
  #2  0x00005555555abc3e in run_next_block (...) at check/main.c:6398
  #3  0x00005555555b0f36 in deal_root_from_list (...) at check/main.c:8408
  #4  0x00005555555b1a3d in check_chunks_and_extents (fs_info=0x5555556a1e30) at check/main.c:8690
  #5  0x00005555555b1e3e in do_check_chunks_and_extents (fs_info=0x5555556a1e30) a
  #6  0x00005555555b5710 in cmd_check (cmd=0x555555696920 <cmd_struct_check>, argc
  #7  0x0000555555568dc7 in cmd_execute (cmd=0x555555696920 <cmd_struct_check>, ar
  #8  0x0000555555569713 in main (argc=2, argv=0x7fffffffde70) at btrfs.c:386

[CAUSE]
This fuzzed images has a corrupted EXTENT_DATA item in data reloc tree:
        item 1 key (256 EXTENT_DATA 256) itemoff 16111 itemsize 12
                generation 0 type 2 (prealloc)
                prealloc data disk byte 16777216 nr 0
                prealloc data offset 0 nr 0

There are several problems with the item:
- Bad item size
  12 is too small.
- Bad key offset
  offset of EXTENT_DATA type key represents file offset, which should
  always be aligned to sector size (4K in this particular case).

[FIX]
Do extra item size and key offset check for original mode, and remove
the abort() call in run_next_block().

And to show off how robust lowmem mode is, lowmem can handle it without
any hiccup.

With this fix, original mode can detect the problem properly:
  Checking filesystem on issue_213.raw
  UUID: 99e50868-0bda-4d89-b0e4-7e8560312ef9
  [1/7] checking root items
  [2/7] checking extents
  ERROR: invalid file extent item size, have 12 expect (21, 16283]
  ERROR: errors found in extent allocation tree or chunk allocation
  [3/7] checking free space cache
  [4/7] checking fs roots
  root 18446744073709551607 root dir 256 error
  root 18446744073709551607 inode 256 errors 62, no orphan item, odd file extent, bad file extent
  ERROR: errors found in fs roots
  found 131072 bytes used, error(s) found
  total csum bytes: 0
  total tree bytes: 131072
  total fs tree bytes: 32768
  total extent tree bytes: 16384
  btree space waste bytes: 124774
  file data blocks allocated: 0
   referenced 0

Issue: #213
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Su Yue <Damenly_Su@gmx.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-01-09 14:27:09 +01:00
..
common.h btrfs-progs: check: move device_record to main.c 2019-10-14 17:27:41 +02:00
main.c btrfs-progs: check/original: Do extra verification on file extent item 2020-01-09 14:27:09 +01:00
mode-common.c btrfs-progs: check/lowmem: Fix a false alert on uninitialized value 2019-11-22 19:09:51 +01:00
mode-common.h btrfs-progs: check/original: Fix inode mode in subvolume trees 2019-11-18 19:21:07 +01:00
mode-lowmem.c btrfs-progs: check/lowmem: Add check and repair for invalid inode generation 2019-11-18 19:21:07 +01:00
mode-lowmem.h btrfs-progs: check/lowmem: Check and repair root generation 2019-09-04 16:06:50 +02:00
mode-original.h btrfs-progs: check/original: Add check and repair for invalid inode generation 2019-11-18 19:21:07 +01:00
qgroup-verify.c btrfs-progs: move qgroup-verify.[ch] to check/ 2019-10-14 17:27:35 +02:00
qgroup-verify.h btrfs-progs: move qgroup-verify.[ch] to check/ 2019-10-14 17:27:35 +02:00