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repair: extent_io.c:603: free_extent_buffer: Assertion `!(eb->flags & 1)' failed. #1

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kakra opened this issue Oct 11, 2011 · 5 comments
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repair: extent_io.c:603: free_extent_buffer: Assertion `!(eb->flags & 1)' failed. #1

kakra opened this issue Oct 11, 2011 · 5 comments

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@kakra
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@kakra kakra commented Oct 11, 2011

free_extent_buffer dumps core after failing an assertion. It looks like the extent has the dirty flag set.

Thank you for developing a btrfs repair utility.
@josefbacik
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@josefbacik josefbacik commented Oct 14, 2011

I've fixed a bunch of shit today, can you give it another go around and see if it's fixed?
@kakra
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@kakra kakra commented Oct 14, 2011

I just pulled in your changes... Apparently the problem persists. BTW: I pulled your changes into integration-20111012 from darksatanic because otherwise I get an error about unsupported features:

jupiter josefbacik-btrfs-progs [git:master] # ./repair /dev/sdd3
couldn't open because of unsupported option features (8).
Could not open root

Anything I can send you for further debugging? The kernel is not able to access some files - it ooopses. That's why I'm trying your repair command - and of course I'd like to support development, btrfs needs a repair command. This is the current output with your latest commits:

jupiter btrfs-progs-unstable [git:integration-20111012-josef] # ./repair /dev/sdd3
Bad node blockptr, deleting
Started transid 48653
Bad node blockptr, deleting
Bad node blockptr, deleting
Checking extent root
Bad node blockptr, deleting
[repeated multiple times]
Bad node blockptr, deleting
repair: extent_io.c:603: free_extent_buffer: Assertion `!(eb->flags & 1)' failed.
Abgebrochen (Speicherabzug geschrieben) #<-- core dumped

I tried commenting out some of the BUG_ON lines but after a few steps of doing so I reach some BUG_ON lines which I should clearly not comment out.
@josefbacik
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@josefbacik josefbacik commented Oct 19, 2011

run it in gdb and do a bt when that happens so I know where it came from.
@kakra
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@kakra kakra commented Oct 20, 2011

Well, this seems not very helpful... Strange thing is: when I tried to run it in gdb before I got meaningfull backtraces.

(gdb) run
Starting program: /usr/src/btrfs-progs-unstable/repair /dev/sdd3
Bad node blockptr, deleting
Started transid 48660
Bad node blockptr, deleting
Checking extent root
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
Bad node blockptr, deleting
repair: extent_io.c:603: free_extent_buffer: Assertion `!(eb->flags & 1)' failed.

Program received signal SIGABRT, Aborted.
0xb7fde424 in __kernel_vsyscall ()
(gdb) bt
#0  0xb7fde424 in __kernel_vsyscall ()
#1  0xb7e57e08 in raise () from /lib/libc.so.6
#2  0xb7e595b3 in abort () from /lib/libc.so.6
#3  0xb7e50a17 in __assert_fail () from /lib/libc.so.6
#4  0x0806b760 in crc32c_table ()
#5  0x0000025b in ?? ()
#6  0x0806b803 in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
josefbacik pushed a commit that referenced this issue Aug 7, 2013
@fdmanana Chris Mason
Btrfs-progs: fix closing of devices
4fbfcaa 
If a device could not be opened in volumes.c:read_one_dev(), a
btrfs_device instance was allocated and added to the list of
devices of the fs - however this device instance had its fd,
name and label fields not initialized. This is problematic in
disk-io.c:close_all_devices() as it tried to sync, fadvise and
close the (invalid) fd of the device, and kfree() its name and
label, which pointed to random memory locations.

  Thread 1 (Thread 0x7f0a3d2d1740 (LWP 23585)):
  #0  __GI___libc_free (mem=0xa5a5a5a5a5a5a5a5) at malloc.c:2970
  #1  0x000000000042054b in close_all_devices (fs_info=0x1e92bf0) at disk-io.c:1276
  #2  0x0000000000421dcd in close_ctree (root=<optimized out>) at disk-io.c:1336
  #3  0x0000000000418cfa in cmd_check (argc=<optimized out>, argv=<optimized out>) at cmds-check.c:4171
  #4  0x0000000000403ed4 in main (argc=2, argv=0x7fff9a583d28) at btrfs.c:295

v2: Added Liu Bo's review mention.

Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
josefbacik pushed a commit that referenced this issue Oct 1, 2014
@adambuchbinder @kdave
btrfs-image: Fix a data race in build_chunk_tree.
c2429c8 
A mdrestore_struct was being written to without its mutex being held.
This race was found with ThreadSanitizer; the relevant part of the report
looks like this:

WARNING: ThreadSanitizer: data race (pid=18828)
  Write of size 8 at 0x7fffffc3d088 by main thread:
    #0 build_chunk_tree .../btrfs-progs/btrfs-image.c:2233
    #1 __restore_metadump .../btrfs-progs/btrfs-image.c:2294
    #2 restore_metadump .../btrfs-progs/btrfs-image.c:2345
    #3 main .../btrfs-progs/btrfs-image.c:2545

  Previous read of size 8 at 0x7fffffc3d088 by thread T1 (mutexes: write M0):
    #0 restore_worker .../btrfs-progs/btrfs-image.c:1636

  Location is stack of main thread.

  Mutex M0 created at:
    #0 pthread_mutex_init ??:0
    #1 mdrestore_init .../btrfs-progs/btrfs-image.c:1766
    #2 __restore_metadump .../btrfs-progs/btrfs-image.c:2286
    #3 restore_metadump .../btrfs-progs/btrfs-image.c:2345
    #4 main .../btrfs-progs/btrfs-image.c:2545

  Thread T1 (tid=18830, running) created by main thread at:
    #0 pthread_create ??:0
    #1 mdrestore_init .../btrfs-progs/btrfs-image.c:1784
    #2 __restore_metadump .../btrfs-progs/btrfs-image.c:2286
    #3 restore_metadump .../btrfs-progs/btrfs-image.c:2345
    #4 main .../btrfs-progs/btrfs-image.c:2545

Signed-off-by: Adam Buchbinder <abuchbinder@google.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
josefbacik pushed a commit that referenced this issue Oct 1, 2014
@adambuchbinder @kdave
btrfs-progs: Fix a use-after-free in the volumes code.
f6a2906 
When a struct btrfs_fs_devices was being torn down by
btrfs_close_devices(), there was an invalidated pointer in the global
list fs_uuids which still pointed to it; if a device was closed and
then reopened (which btrfs-convert does), freed memory would be
accessed.

This was found using ThreadSanitizer (pretty much doing what
AddressSanitizer would, but not exiting after the first failure).
To reproduce, build with -fsanitize=thread and run 'make test'.
Representative output is below.

This change makes the current tests TSan-clean.

WARNING: ThreadSanitizer: heap-use-after-free (pid=29161)
  Read of size 8 at 0x7d180000eee0 by main thread:
    #0 memcmp ??:0
    #1 find_fsid .../volumes.c:81
    #2 device_list_add .../volumes.c:95
    #3 btrfs_scan_one_device .../volumes.c:259
    #4 btrfs_scan_fs_devices .../disk-io.c:1002
    #5 __open_ctree_fd .../disk-io.c:1090
    #6 open_ctree_fd .../disk-io.c:1191
    #7 do_convert .../btrfs-convert.c:2317
    #8 main .../btrfs-convert.c:2745

  Previous write of size 8 at 0x7d180000eee0 by main thread:
    #0 free ??:0
    #1 btrfs_close_devices .../volumes.c:191
    #2 close_ctree .../disk-io.c:1401
    #3 do_convert .../btrfs-convert.c:2300
    #4 main .../btrfs-convert.c:2745

  Location is heap block of size 96 at 0x7d180000eee0 allocated by main thread:
    #0 calloc ??:0 (exe+0x00000002acc6)
    #1 device_list_add .../volumes.c:97
    #2 btrfs_scan_one_device .../volumes.c:259
    #3 btrfs_scan_fs_devices .../disk-io.c:1002
    #4 __open_ctree_fd .../disk-io.c:1090
    #5 open_ctree_fd .../disk-io.c:1191
    #6 do_convert .../btrfs-convert.c:2256
    #7 main .../btrfs-convert.c:2745

Signed-off-by: Adam Buchbinder <abuchbinder@google.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
josefbacik pushed a commit that referenced this issue Sep 29, 2017
@pmhahn @kdave
btrfs-progs: Fix slot >= nritems
1618d8a 
Running "btrfsck --repair /dev/sdd2" crashed as it can happen in
(corrupted) file systems, that slot > nritems:
> (gdb) bt full
> #0  0x00007ffff7020e71 in __memmove_sse2_unaligned_erms () from /lib/x86_64-linux-gnu/libc.so.6
> #1  0x0000000000438764 in btrfs_del_ptr (trans=<optimized out>, root=0x6e4fe0, path=0x1d17880, level=0, slot=7)
>     at ctree.c:2611
>         parent = 0xcd96980
>         nritems = <optimized out>
>         __func__ = "btrfs_del_ptr"
> #2  0x0000000000421b15 in repair_btree (corrupt_blocks=<optimized out>, root=<optimized out>) at cmds-check.c:3539
>         key = {objectid = 77990592512, type = 168 '\250', offset = 16384}
>         trans = 0x8f48c0
>         path = 0x1d17880
>         level = 0
> #3  check_fs_root (wc=<optimized out>, root_cache=<optimized out>, root=<optimized out>) at cmds-check.c:3703
>         corrupt = 0x1d17880
>         corrupt_blocks = {root = {rb_node = 0x6e80c60}}
>         path = {nodes = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, slots = {0, 0, 0, 0, 0, 0, 0, 0}, locks = {0, 0,
>             0, 0, 0, 0, 0, 0}, reada = 0, lowest_level = 0, search_for_split = 0, skip_check_block = 0}
>         nrefs = {bytenr = {271663104, 271646720, 560021504, 0, 0, 0, 0, 0}, refs = {1, 1, 1, 0, 0, 0, 0, 0}}
>         wret = 215575372
>         root_node = {cache = {rb_node = {__rb_parent_color = 0, rb_right = 0x0, rb_left = 0x0}, objectid = 0,
>             start = 0, size = 0}, root_cache = {root = {rb_node = 0x0}}, inode_cache = {root = {
>               rb_node = 0x781c80}}, current = 0x819530, refs = 0}
>         status = 215575372
>         rec = 0x1
> #4  check_fs_roots (root_cache=0xcd96b6d, root=<optimized out>) at cmds-check.c:3809
>         path = {nodes = {0x6eed90, 0x6a2f40, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, slots = {18, 2, 0, 0, 0, 0, 0, 0},
>           locks = {0, 0, 0, 0, 0, 0, 0, 0}, reada = 0, lowest_level = 0, search_for_split = 0,
>           skip_check_block = 0}
>         key = {objectid = 323, type = 132 '\204', offset = 18446744073709551615}
>         wc = {shared = {root = {rb_node = 0x0}}, nodes = {0x0, 0x0, 0x7fffffffe428, 0x0, 0x0, 0x0, 0x0, 0x0},
>           active_node = 2, root_level = 2}
>         leaf = 0x6e4fe0
>         tmp_root = 0x6e4fe0
> #5  0x00000000004287c3 in cmd_check (argc=215575372, argv=0x1d17880) at cmds-check.c:11521
>         root_cache = {root = {rb_node = 0x98c2940}}
>         info = 0x6927b0
>         bytenr = 6891440
>         tree_root_bytenr = 0
>         uuidbuf = "f65ff1a1-76ef-456e-beb5-c6c3841e7534"
>         num = 215575372
>         readonly = 218080104
>         qgroups_repaired = 0
> #6  0x000000000040a41f in main (argc=3, argv=0x7fffffffebe8) at btrfs.c:243
>         cmd = 0x689868
>         bname = <optimized out>
>         ret = <optimized out>

in that case the count of remaining items (nritems - slot - 1) gets
negative. That is then casted to (unsigned long len), which leads to the
observed crash.

Change the tests before the move to handle only the non-corrupted case,
were slow < nritems.

This does not fix the corruption, but allows btrfsck to finish without
crashing.

Signed-off-by: Philipp Hahn <hahn@univention.de>
Signed-off-by: David Sterba <dsterba@suse.com>
josefbacik pushed a commit that referenced this issue Sep 29, 2017
@adambuchbinder @kdave
btrfs-progs: convert: Fix data race when reporting progress
1639cc2 
The status display was reading the state while the task was updating
it. Use a mutex to prevent the race.

This race was detected using ThreadSanitizer and
misc-tests/005-convert-progress-thread-crash.

==================
WARNING: ThreadSanitizer: data race
  Write of size 8 by main thread:
    #0 ext2_copy_inodes btrfs-progs/convert/source-ext2.c:853
    #1 copy_inodes btrfs-progs/convert/main.c:145
    #2 do_convert btrfs-progs/convert/main.c:1297
    #3 main btrfs-progs/convert/main.c:1924

  Previous read of size 8 by thread T1:
    #0 print_copied_inodes btrfs-progs/convert/main.c:124

  Location is stack of main thread.

  Thread T1 (running) created by main thread at:
    #0 pthread_create <null>
    #1 task_start btrfs-progs/task-utils.c:50
    #2 do_convert btrfs-progs/convert/main.c:1295
    #3 main btrfs-progs/convert/main.c:1924

SUMMARY: ThreadSanitizer: data race
btrfs-progs/convert/source-ext2.c:853 in ext2_copy_inodes

Signed-off-by: Adam Buchbinder <abuchbinder@google.com>
Signed-off-by: David Sterba <dsterba@suse.com>
josefbacik pushed a commit that referenced this issue Sep 29, 2017
@adambuchbinder @kdave
btrfs-progs: image: Fix data races when reporting progress
76daaec 
Making the code data-race safe requires that reads *and* writes
happen under a mutex lock, if any of the access are writes. See
Dmitri Vyukov, "Benign data races: what could possibly go wrong?"
for more details.

The fix here was to put most of the main loop of restore_worker
under a mutex lock.

This race was detected using fsck-tests/012-leaf-corruption.

==================
WARNING: ThreadSanitizer: data race
  Write of size 4 by main thread:
    #0 add_cluster btrfs-progs/image/main.c:1931
    #1 restore_metadump btrfs-progs/image/main.c:2566
    #2 main btrfs-progs/image/main.c:2859

  Previous read of size 4 by thread T6:
    #0 restore_worker btrfs-progs/image/main.c:1720

  Location is stack of main thread.

  Thread T6 (running) created by main thread at:
    #0 pthread_create <null>
    #1 mdrestore_init btrfs-progs/image/main.c:1868
    #2 restore_metadump btrfs-progs/image/main.c:2534
    #3 main btrfs-progs/image/main.c:2859

SUMMARY: ThreadSanitizer: data race btrfs-progs/image/main.c:1931 in
add_cluster

Signed-off-by: Adam Buchbinder <abuchbinder@google.com>
Signed-off-by: David Sterba <dsterba@suse.com>
@kakra
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@kakra kakra commented Oct 28, 2017

Didn't see this problem in a long time...
@kakra kakra closed this Oct 28, 2017
josefbacik pushed a commit that referenced this issue Jan 9, 2020
@adam900710 @kdave
btrfs-progs: btrfs-progs: Fix read beyond boundary bug in build_roots…
5424611 
…_info_cache()

This bug is exposed by fsck-test with D=asan, hit by test case 020, with
the following error report:

=================================================================
==10740==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x621000061580 at pc 0x56051f0db6cd bp 0x7ffe170f3e20 sp 0x7ffe170f3e10
READ of size 1 at 0x621000061580 thread T0
    #0 0x56051f0db6cc in btrfs_extent_inline_ref_type /home/adam/btrfs/btrfs-progs/ctree.h:1727
    #1 0x56051f13b669 in build_roots_info_cache /home/adam/btrfs/btrfs-progs/cmds-check.c:14306
    #2 0x56051f13c86a in repair_root_items /home/adam/btrfs/btrfs-progs/cmds-check.c:14450
    #3 0x56051f13ea89 in cmd_check /home/adam/btrfs/btrfs-progs/cmds-check.c:14965
    #4 0x56051efe75bb in main /home/adam/btrfs/btrfs-progs/btrfs.c:302
    #5 0x7f04ddbb0f49 in __libc_start_main (/usr/lib/libc.so.6+0x20f49)
    #6 0x56051efe68c9 in _start (/home/adam/btrfs/btrfs-progs/btrfs+0x5b8c9)

0x621000061580 is located 0 bytes to the right of 4224-byte region [0x621000060500,0x621000061580)
allocated by thread T0 here:
    #0 0x7f04ded50ce1 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:70
    #1 0x56051f04685e in __alloc_extent_buffer /home/adam/btrfs/btrfs-progs/extent_io.c:553
    #2 0x56051f047563 in alloc_extent_buffer /home/adam/btrfs/btrfs-progs/extent_io.c:687
    #3 0x56051efff1d1 in btrfs_find_create_tree_block /home/adam/btrfs/btrfs-progs/disk-io.c:187
    #4 0x56051f000133 in read_tree_block /home/adam/btrfs/btrfs-progs/disk-io.c:327
    #5 0x56051efeddb8 in read_node_slot /home/adam/btrfs/btrfs-progs/ctree.c:652
    #6 0x56051effb0d9 in btrfs_next_leaf /home/adam/btrfs/btrfs-progs/ctree.c:2853
    #7 0x56051f13b343 in build_roots_info_cache /home/adam/btrfs/btrfs-progs/cmds-check.c:14267
    #8 0x56051f13c86a in repair_root_items /home/adam/btrfs/btrfs-progs/cmds-check.c:14450
    #9 0x56051f13ea89 in cmd_check /home/adam/btrfs/btrfs-progs/cmds-check.c:14965
    #10 0x56051efe75bb in main /home/adam/btrfs/btrfs-progs/btrfs.c:302
    #11 0x7f04ddbb0f49 in __libc_start_main (/usr/lib/libc.so.6+0x20f49)

It's completely possible that one extent/metadata item has no inline
reference, while build_roots_info_cache() doesn't have such check.

Fix it by checking @iref against item end to avoid such problem.

Issue: #92
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
josefbacik pushed a commit that referenced this issue Jan 9, 2020
@adam900710 @kdave
btrfs-progs: delayed-ref: Fix memory leak and use-after-free caused b…
a1dce63 
…y wrong condition to free delayed ref/head.

[BUG]
When btrfs-progs is compiled with D=asan, it can't pass even the very
basic fsck tests due to btrfs-image has memory leak:
  === START TEST /home/adam/btrfs/btrfs-progs/tests//fsck-tests/001-bad-file-extent-bytenr
  restoring image default_case.img

  =================================================================
  ==7790==ERROR: LeakSanitizer: detected memory leaks

  Direct leak of 104 byte(s) in 1 object(s) allocated from:
      #0 0x7f1d3b738389 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86
      #1 0x560ca6b7f4ff in btrfs_add_delayed_tree_ref /home/adam/btrfs/btrfs-progs/delayed-ref.c:569
      #2 0x560ca6af2d0b in btrfs_free_extent /home/adam/btrfs/btrfs-progs/extent-tree.c:2155
      #3 0x560ca6ac16ca in __btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:319
      #4 0x560ca6ac1d8c in btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:383
      #5 0x560ca6ac6c8e in btrfs_search_slot /home/adam/btrfs/btrfs-progs/ctree.c:1153
      #6 0x560ca6ab7e83 in fixup_device_size image/main.c:2113
      #7 0x560ca6ab9279 in fixup_chunks_and_devices image/main.c:2333
      #8 0x560ca6ab9ada in restore_metadump image/main.c:2455
      #9 0x560ca6abaeba in main image/main.c:2723
      #10 0x7f1d3b148ce2 in __libc_start_main (/usr/lib/libc.so.6+0x23ce2)

  ... tons of similar leakage for delayed_tree_ref ...

  Direct leak of 96 byte(s) in 1 object(s) allocated from:
      #0 0x7f1d3b738389 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86
      #1 0x560ca6b7f5fb in btrfs_add_delayed_tree_ref /home/adam/btrfs/btrfs-progs/delayed-ref.c:583
      #2 0x560ca6af5679 in alloc_tree_block /home/adam/btrfs/btrfs-progs/extent-tree.c:2503
      #3 0x560ca6af57ac in btrfs_alloc_free_block /home/adam/btrfs/btrfs-progs/extent-tree.c:2524
      #4 0x560ca6ac115b in __btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:290
      #5 0x560ca6ac1d8c in btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:383
      #6 0x560ca6b7bb15 in commit_tree_roots /home/adam/btrfs/btrfs-progs/transaction.c:98
      #7 0x560ca6b7c525 in btrfs_commit_transaction /home/adam/btrfs/btrfs-progs/transaction.c:192
      #8 0x560ca6ab92be in fixup_chunks_and_devices image/main.c:2337
      #9 0x560ca6ab9ada in restore_metadump image/main.c:2455
      #10 0x560ca6abaeba in main image/main.c:2723
      #11 0x7f1d3b148ce2 in __libc_start_main (/usr/lib/libc.so.6+0x23ce2)

  ... tons of similar leakage for delayed_ref_head ...

  SUMMARY: AddressSanitizer: 1600 byte(s) leaked in 16 allocation(s).
  failed to restore image ./default_case.img

[CAUSE]
Commit c603970 ("btrfs-progs: Add delayed refs infrastructure")
introduces delayed ref infrastructure for free space tree, however the
refcount_dec_and_test() from kernel code is wrongly backported.

refcount_dec_and_test() will return true if the refcount reaches 0.
So kernel code will free the allocated space as expected:
	if (refcount_dec_and_test(&ref->refs)) {
		kmem_cache_free();
	}

However btrfs-progs backport is using the opposite condition:
	if (--ref->refs) {
		kfree();
	}

This will not free the memory for the last user, but for refs >= 2.
Causing both use-after-free and memory leak for any offline write
operation.

[FIX]
Fix the (--ref->refs) condition to (--ref->refs == 0) to fix the
backport error.

Fixes: c603970 ("btrfs-progs: Add delayed refs infrastructure")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
josefbacik pushed a commit that referenced this issue Jul 20, 2020
@adam900710 @kdave
btrfs-progs: check/original: Do extra verification on file extent item
3dcce48 
[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>
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@kakra @josefbacik
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