syzbot


possible deadlock in hfsplus_block_free (5)

Status: upstream: reported on 2026/05/04 02:29
Reported-by: syzbot+b35985b59161736b860d@syzkaller.appspotmail.com
First crash: 2d07h, last: 2d06h
Similar bugs (15)
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 697d 697d 0/3 auto-obsoleted due to no activity on 2024/09/15 13:42
linux-5.15 possible deadlock in hfsplus_block_free (4) 4 1 192d 192d 0/3 auto-obsoleted due to no activity on 2026/02/02 10:58
linux-4.14 possible deadlock in hfsplus_block_free hfsplus 4 10 1166d 1251d 0/1 upstream: reported on 2022/12/01 19:36
linux-6.1 possible deadlock in hfsplus_block_free (6) 4 3 1d23h 4d21h 0/3 upstream: reported on 2026/05/01 12:21
linux-6.1 possible deadlock in hfsplus_block_free (5) 4 1 123d 123d 0/3 auto-obsoleted due to no activity on 2026/04/13 08:07
linux-5.15 possible deadlock in hfsplus_block_free (3) 4 2 427d 429d 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 1157d 1248d 0/1 upstream: reported on 2022/12/04 19:32
linux-6.1 possible deadlock in hfsplus_block_free (4) 4 1 230d 230d 0/3 auto-obsoleted due to no activity on 2025/12/27 09:21
upstream possible deadlock in hfsplus_block_free hfs 4 C inconclusive error 392 22d 1254d 0/29 upstream: reported C repro on 2022/11/29 08:32
linux-5.15 possible deadlock in hfsplus_block_free 4 20 925d 1129d 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 381d 443d 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 697d 697d 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 851d 1115d 0/3 auto-obsoleted due to no activity on 2024/04/14 19:02
linux-6.6 possible deadlock in hfsplus_block_free (2) 4 1 118d 118d 0/2 auto-obsoleted due to no activity on 2026/04/17 20:22
linux-6.6 possible deadlock in hfsplus_block_free 4 1 230d 230d 0/2 auto-obsoleted due to no activity on 2025/12/26 20:38

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/5394 is trying to acquire lock:
ffff8880251ed0f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_free+0xc1/0x4d0 fs/hfsplus/bitmap.c:182

but task is already holding lock:
ffff888078749c08 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x2c6/0xb80 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+0x1e3/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hfsplus_get_block+0x3a1/0x15a0 fs/hfsplus/extents.c:260
       block_read_full_page+0x306/0xd40 fs/buffer.c:2290
       do_read_cache_page+0x8a1/0x1030 mm/filemap.c:-1
       read_mapping_page include/linux/pagemap.h:515 [inline]
       hfsplus_block_allocate+0xf1/0x910 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xb1f/0x1a50 fs/hfsplus/extents.c:466
       hfsplus_get_block+0x430/0x15a0 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x565/0x15d0 fs/buffer.c:2012
       __block_write_begin fs/buffer.c:2062 [inline]
       block_write_begin fs/buffer.c:2122 [inline]
       cont_write_begin+0x598/0x7b0 fs/buffer.c:2471
       hfsplus_write_begin+0x92/0xe0 fs/hfsplus/inode.c:53
       __page_symlink+0x102/0x200 fs/namei.c:5199
       hfsplus_symlink+0xc6/0x260 fs/hfsplus/dir.c:449
       vfs_symlink+0x247/0x3d0 fs/namei.c:4437
       do_symlinkat+0x1ab/0x6b0 fs/namei.c:4466
       __do_sys_symlink fs/namei.c:4488 [inline]
       __se_sys_symlink fs/namei.c:4486 [inline]
       __x64_sys_symlink+0x7a/0x90 fs/namei.c:4486
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&sbi->alloc_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hfsplus_block_free+0xc1/0x4d0 fs/hfsplus/bitmap.c:182
       hfsplus_free_extents+0x10d/0xa50 fs/hfsplus/extents.c:360
       hfsplus_file_truncate+0x783/0xb80 fs/hfsplus/extents.c:589
       hfsplus_delete_inode+0x17c/0x230 fs/hfsplus/inode.c:-1
       hfsplus_unlink+0x4f7/0x7b0 fs/hfsplus/dir.c:405
       vfs_unlink+0x385/0x600 fs/namei.c:4288
       do_unlinkat+0x391/0x710 fs/namei.c:4356
       __do_sys_unlink fs/namei.c:4404 [inline]
       __se_sys_unlink fs/namei.c:4402 [inline]
       __x64_sys_unlink+0x45/0x50 fs/namei.c:4402
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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/5394:
 #0: ffff88807a838460 (sb_writers#18){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff88807874ab80 (&type->i_mutex_dir_key#10/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
 #1: ffff88807874ab80 (&type->i_mutex_dir_key#10/1){+.+.}-{3:3}, at: do_unlinkat+0x1c8/0x710 fs/namei.c:4339
 #2: ffff888078749e00 (&sb->s_type->i_mutex_key#26){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #2: ffff888078749e00 (&sb->s_type->i_mutex_key#26){+.+.}-{3:3}, at: vfs_unlink+0xee/0x600 fs/namei.c:4277
 #3: ffff8880251ed198 (&sbi->vh_mutex){+.+.}-{3:3}, at: hfsplus_unlink+0x175/0x7b0 fs/hfsplus/dir.c:370
 #4: ffff888078749c08 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x2c6/0xb80 fs/hfsplus/extents.c:574

stack backtrace:
CPU: 0 PID: 5394 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 hfsplus_block_free+0xc1/0x4d0 fs/hfsplus/bitmap.c:182
 hfsplus_free_extents+0x10d/0xa50 fs/hfsplus/extents.c:360
 hfsplus_file_truncate+0x783/0xb80 fs/hfsplus/extents.c:589
 hfsplus_delete_inode+0x17c/0x230 fs/hfsplus/inode.c:-1
 hfsplus_unlink+0x4f7/0x7b0 fs/hfsplus/dir.c:405
 vfs_unlink+0x385/0x600 fs/namei.c:4288
 do_unlinkat+0x391/0x710 fs/namei.c:4356
 __do_sys_unlink fs/namei.c:4404 [inline]
 __se_sys_unlink fs/namei.c:4402 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4402
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4c80e5fec7
Code: 73 01 c3 48 c7 c1 e8 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 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffc5d4edc98 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4c80e5fec7
RDX: 00007ffc5d4edcc0 RSI: 00007ffc5d4edd50 RDI: 00007ffc5d4edd50
RBP: 00007ffc5d4edd50 R08: 00007ffc5d4eed50 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffc5d4eee40
R13: 00007f4c80ef6120 R14: 0000000000028874 R15: 00007ffc5d4eff10
 </TASK>
hfsplus: invalid file type 0174377 for inode 21
hfsplus: invalid file type 0174377 for inode 21

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/04 02:56 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_free
2026/05/04 02:47 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_free
2026/05/04 02:45 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_free
2026/05/04 02:45 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_free
2026/05/04 02:44 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_free
2026/05/04 02:41 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_free
2026/05/04 02:28 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_free
* Struck through repros no longer work on HEAD.