syzbot


possible deadlock in hfsplus_block_free

Status: upstream: reported on 2025/09/17 20:37
Reported-by: syzbot+410d7ac6d83199282250@syzkaller.appspotmail.com
First crash: 17h40m, last: 17h40m
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in hfsplus_block_free (2) 4 4 468d 468d 0/3 auto-obsoleted due to no activity on 2024/09/15 13:42
linux-4.14 possible deadlock in hfsplus_block_free hfsplus 4 10 936d 1021d 0/1 upstream: reported on 2022/12/01 19:36
linux-5.15 possible deadlock in hfsplus_block_free (3) 4 2 197d 199d 0/3 auto-obsoleted due to no activity on 2025/06/13 01:35
linux-4.19 possible deadlock in hfsplus_block_free hfsplus 4 20 927d 1018d 0/1 upstream: reported on 2022/12/04 19:32
linux-6.1 possible deadlock in hfsplus_block_free (4) 4 1 4h56m 4h56m 0/3 upstream: reported on 2025/09/18 09:21
upstream possible deadlock in hfsplus_block_free hfs 4 C inconclusive error 323 11d 1024d 0/29 upstream: reported C repro on 2022/11/29 08:32
linux-5.15 possible deadlock in hfsplus_block_free 4 20 695d 899d 0/3 auto-obsoleted due to no activity on 2024/01/31 18:41
linux-6.1 possible deadlock in hfsplus_block_free (3) 4 4 151d 213d 0/3 auto-obsoleted due to no activity on 2025/07/29 00:39
linux-5.15 possible deadlock in hfsplus_block_free (2) 4 1 468d 468d 0/3 auto-obsoleted due to no activity on 2024/09/15 11:28
linux-6.1 possible deadlock in hfsplus_block_free 4 27 621d 885d 0/3 auto-obsoleted due to no activity on 2024/04/14 19:02

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/7416 is trying to acquire lock:
ffff888024cbf0f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_free+0xc3/0x4b0 fs/hfsplus/bitmap.c:182

but task is already holding lock:
ffff88802431c488 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x293/0xb40 fs/hfsplus/extents.c:574

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       hfsplus_get_block+0x39f/0x1530 fs/hfsplus/extents.c:260
       block_read_full_folio+0x42e/0xf40 fs/buffer.c:2406
       filemap_read_folio+0x167/0x760 mm/filemap.c:2420
       do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3789
       do_read_cache_page+0x32/0x250 mm/filemap.c:3855
       read_mapping_page include/linux/pagemap.h:892 [inline]
       hfsplus_block_allocate+0xff/0x8e0 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
       hfsplus_get_block+0x412/0x1530 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
       __block_write_begin fs/buffer.c:2173 [inline]
       block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
       cont_write_begin+0x5c8/0x7e0 fs/buffer.c:2591
       hfsplus_write_begin+0x8b/0xd0 fs/hfsplus/inode.c:52
       generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4016
       generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4137
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x43b/0x940 fs/read_write.c:584
       ksys_write+0x147/0x250 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&sbi->alloc_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       hfsplus_block_free+0xc3/0x4b0 fs/hfsplus/bitmap.c:182
       hfsplus_free_extents+0x10d/0xa50 fs/hfsplus/extents.c:360
       hfsplus_file_truncate+0x735/0xb40 fs/hfsplus/extents.c:589
       hfsplus_delete_inode+0x180/0x230 fs/hfsplus/inode.c:-1
       hfsplus_unlink+0x4e4/0x730 fs/hfsplus/dir.c:405
       vfs_unlink+0x389/0x600 fs/namei.c:4325
       do_unlinkat+0x328/0x570 fs/namei.c:4391
       __do_sys_unlink fs/namei.c:4439 [inline]
       __se_sys_unlink fs/namei.c:4437 [inline]
       __x64_sys_unlink+0x49/0x50 fs/namei.c:4437
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&HFSPLUS_I(inode)->extents_lock);
                               lock(&sbi->alloc_mutex);
                               lock(&HFSPLUS_I(inode)->extents_lock);
  lock(&sbi->alloc_mutex);

 *** DEADLOCK ***

5 locks held by syz-executor/7416:
 #0: ffff8880263aa418 (sb_writers#26){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:403
 #1: ffff88807a0175d0 (&type->i_mutex_dir_key#16
/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
/1){+.+.}-{3:3}, at: do_unlinkat+0x17c/0x570 fs/namei.c:4376
 #2: ffff88802431c690 (&sb->s_type->i_mutex_key#34
){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
){++++}-{3:3}, at: vfs_unlink+0xf2/0x600 fs/namei.c:4314
 #3: ffff888024cbf198 (&sbi->vh_mutex){+.+.}-{3:3}, at: hfsplus_unlink+0x161/0x730 fs/hfsplus/dir.c:370
 #4: ffff88802431c488 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x293/0xb40 fs/hfsplus/extents.c:574

stack backtrace:
CPU: 1 PID: 7416 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 hfsplus_block_free+0xc3/0x4b0 fs/hfsplus/bitmap.c:182
 hfsplus_free_extents+0x10d/0xa50 fs/hfsplus/extents.c:360
 hfsplus_file_truncate+0x735/0xb40 fs/hfsplus/extents.c:589
 hfsplus_delete_inode+0x180/0x230 fs/hfsplus/inode.c:-1
 hfsplus_unlink+0x4e4/0x730 fs/hfsplus/dir.c:405
 vfs_unlink+0x389/0x600 fs/namei.c:4325
 do_unlinkat+0x328/0x570 fs/namei.c:4391
 __do_sys_unlink fs/namei.c:4439 [inline]
 __se_sys_unlink fs/namei.c:4437 [inline]
 __x64_sys_unlink+0x49/0x50 fs/namei.c:4437
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7efda498e157
Code: 73 01 c3 48 c7 c1 a8 ff ff ff 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 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd39673d98 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007efda498e157
RDX: 00007ffd39673dc0 RSI: 00007ffd39673e50 RDI: 00007ffd39673e50
RBP: 00007ffd39673e50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffd39674f40
R13: 00007efda4a11c05 R14: 0000000000079e33 R15: 00007ffd39676010
 </TASK>
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent
hfsplus: invalid extended attribute record
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/17 20:37 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in hfsplus_block_free
* Struck through repros no longer work on HEAD.