possible deadlock in hfs_extend_file (3)

Status: upstream: reported C repro on 2024/04/18 14:41
Subsystems: hfs
[Documentation on labels]
Reported-by: syzbot+2a62f58f1a4951a549bb@syzkaller.appspotmail.com
First crash: 875d, last: 1d08h
Cause bisection: introduced by (bisect log) [merge commit]:
commit e8c3f6322cc853084a6d63244c15fb0251090327
Author: Arnd Bergmann <arnd@arndb.de>
Date: Thu Oct 11 13:21:40 2018 +0000

  Merge tag 'imx-defconfig-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux into next/defconfig

Crash: lost connection to test machine (log)
Repro: C syz .config
  
✨ AI Jobs (8)
ID Workflow Result Correct Bug Created Started Finished Revision
a7852ebc assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/09/04 04:04 2026/09/04 04:04 2026/09/04 04:06 d2e5fb95
31848459 assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/08/05 00:03 2026/08/05 00:03 2026/08/05 00:03 d4abbeac
d8ff848a assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/07/05 04:22 2026/07/05 04:22 2026/07/05 04:25 93f57954
c64ade94 assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/06/18 04:00 2026/06/18 04:00 2026/06/18 04:01 b62b3ded
351e65a9 assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/06/10 00:01 2026/06/10 00:01 2026/06/10 00:04 c36c07f6
ceed0071 assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/06/04 01:55 2026/06/04 01:55 2026/06/04 01:57 62fe1528
57add41d assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/06/01 13:18 2026/06/01 13:18 2026/06/01 13:21 6b4a8443
833efe6b assessment-security 💥 possible deadlock in hfs_extend_file (3) 2026/05/15 22:32 2026/05/15 22:32 2026/05/15 22:34 efdaf0f9
Discussions (12)
Title Replies (including bot) Last reply
[syzbot] Monthly hfs report (Sep 2026) 0 (1) 2026/09/04 20:33
[syzbot] Monthly hfs report (Aug 2026) 0 (1) 2026/08/05 00:00
[syzbot] Monthly hfs report (Jul 2026) 0 (1) 2026/07/04 12:32
[syzbot] Monthly hfs report (Jun 2026) 0 (1) 2026/06/03 04:32
[syzbot] Monthly hfs report (May 2026) 0 (1) 2026/05/02 20:32
[syzbot] Monthly hfs report (Apr 2026) 0 (1) 2026/04/01 13:15
[syzbot] Monthly hfs report (Mar 2026) 0 (1) 2026/03/03 08:06
[syzbot] Monthly hfs report (Jan 2026) 0 (1) 2026/01/29 10:20
[syzbot] Monthly hfs report (Dec 2025) 0 (1) 2025/12/29 10:22
[syzbot] Monthly hfs report (Oct 2025) 0 (1) 2025/10/27 12:50
[syzbot] [hfs?] possible deadlock in hfs_extend_file (3) 0 (2) 2024/06/23 09:36
[PATCH fs/hfs] hfs: fix deadlock in hfs_extend_file() 1 (1) 2024/04/23 09:31
Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 possible deadlock in hfs_extend_file hfs 4 1 1349d 1349d 0/1 upstream: reported on 2022/12/27 15:22
linux-5.15 possible deadlock in hfs_extend_file (2) 4 1 1049d 1049d 0/3 auto-obsoleted due to no activity on 2024/01/31 18:25
linux-6.1 possible deadlock in hfs_extend_file 4 7 1086d 1273d 0/3 auto-obsoleted due to no activity on 2023/12/24 21:20
upstream possible deadlock in hfs_extend_file hfs 4 46 1110d 1354d 0/29 auto-obsoleted due to no activity on 2023/11/06 09:48
linux-6.1 possible deadlock in hfs_extend_file (2) origin:upstream 4 syz, C 238 10d 885d 0/3 upstream: reported C repro on 2024/04/04 03:11
linux-5.15 possible deadlock in hfs_extend_file (3) origin:upstream 4 syz, C 216 12d 907d 0/3 upstream: reported C repro on 2024/03/13 05:11
linux-6.6 possible deadlock in hfs_extend_file origin:upstream missing-backport 4 syz, C error 130 15d 446d 0/2 upstream: reported C repro on 2025/06/17 13:12
upstream possible deadlock in hfs_extend_file (2) hfs 4 syz, C done done 4 978d 999d 0/29 auto-obsoleted due to no activity on 2024/04/11 05:11
linux-5.15 possible deadlock in hfs_extend_file 4 5 1174d 1238d 0/3 auto-obsoleted due to no activity on 2023/09/28 05:53
Last patch testing requests (1)
Created Duration User Patch Repo Result
2024/08/31 11:43 59m retest repro upstream report log

Sample crash report:
WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/5962 is trying to acquire lock:
ffff8880315e0128 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x14c0 fs/hfs/extent.c:397

but task is already holding lock:
ffff8880315e0868 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x14c0 fs/hfs/extent.c:397

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&HFS_I(tree->inode)->extents_lock);
  lock(&HFS_I(tree->inode)->extents_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz.0.17/5962:
 #0: ffff8880387b4480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:508
 #1: ffff888030d20300 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:980 [inline]
 #1: ffff888030d20300 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: open_last_lookups fs/namei.c:3892 [inline]
 #1: ffff888030d20300 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: path_openat+0x8e6/0x3840 fs/namei.c:4131
 #2: ffff88803866a0a0 (&tree->tree_lock){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x2c0 fs/hfs/bfind.c:-1
 #3: ffff8880315e0868 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x14c0 fs/hfs/extent.c:397
 #4: ffff8880386680a0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x2c0 fs/hfs/bfind.c:-1

stack backtrace:
CPU: 1 UID: 0 PID: 5962 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3895
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547
 hfs_extend_file+0xda/0x14c0 fs/hfs/extent.c:397
 hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x31e/0x14c0 fs/hfs/extent.c:401
 hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
 hfs_cat_create+0x1c5/0x730 fs/hfs/catalog.c:104
 hfs_create+0x66/0xe0 fs/hfs/dir.c:202
 lookup_open fs/namei.c:3796 [inline]
 open_last_lookups fs/namei.c:3895 [inline]
 path_openat+0x1500/0x3840 fs/namei.c:4131
 do_filp_open+0x1fa/0x410 fs/namei.c:4161
 do_sys_openat2+0x121/0x1c0 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_open fs/open.c:1460 [inline]
 __se_sys_open fs/open.c:1456 [inline]
 __x64_sys_open+0x11e/0x150 fs/open.c:1456
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd0b1c0eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007fff6de76808 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fd0b1e65fa0 RCX: 00007fd0b1c0eec9
RDX: 0000000000000000 RSI: 000000000014927e RDI: 0000200000000180
RBP: 00007fd0b1c91f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd0b1e65fa0 R14: 00007fd0b1e65fa0 R15: 0000000000000003
 </TASK>

Crashes (5962):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/10 14:43 upstream 5472d60c129f ff1712fe .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs possible deadlock in hfs_extend_file
2024/06/23 09:36 upstream 563a50672d8a edc5149a .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-upstream-fs possible deadlock in hfs_extend_file
2025/10/10 12:48 upstream 5472d60c129f ff1712fe .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2024/12/13 13:29 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 2e7aff49b5da 3547e30f .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci-upstream-gce-arm64 possible deadlock in hfs_extend_file
2026/09/04 19:05 upstream bc35965f6940 f65209a4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/04 14:34 upstream bc35965f6940 f65209a4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/03 18:10 upstream 8ab1afb2eb24 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/02 21:22 upstream 89a312991dc6 85995287 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/02 10:57 upstream 89a312991dc6 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/02 09:49 upstream 89a312991dc6 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/02 04:45 upstream 89a312991dc6 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/01 23:18 upstream 786262be6048 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/01 21:13 upstream 786262be6048 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/01 15:46 upstream 786262be6048 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/01 06:16 upstream bf1079577a11 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/01 04:09 upstream bf1079577a11 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/09/01 03:58 upstream bf1079577a11 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/31 19:20 upstream cee9395acd80 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/31 16:44 upstream cee9395acd80 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/31 02:39 upstream a23cbb05744b 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/30 17:38 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/30 15:28 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/30 08:22 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/30 06:39 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/30 04:06 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/29 21:27 upstream cf72cbb39da8 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/29 19:12 upstream cf72cbb39da8 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/29 15:01 upstream cf72cbb39da8 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/29 11:38 upstream cf72cbb39da8 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/28 19:15 upstream c20313e98b04 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/28 12:17 upstream 1b78070aaef6 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/28 01:54 upstream 1b78070aaef6 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/27 23:47 upstream 18fbf5151d2c e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in hfs_extend_file
2026/08/27 22:40 upstream 73e3f0710014 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/27 19:50 upstream 73e3f0710014 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/27 18:36 upstream 73e3f0710014 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in hfs_extend_file
2026/08/27 15:55 upstream 73e3f0710014 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in hfs_extend_file
2024/06/23 20:30 upstream 7c16f0a4ed1c edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in hfs_extend_file
2024/06/21 22:01 upstream 66cc544fd75c edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in hfs_extend_file
2024/04/14 14:39 upstream fe46a7dd189e c8349e48 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in hfs_extend_file
2026/09/05 09:56 upstream 654ae5d73c05 4f7b22a0 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2026/09/05 04:46 upstream 654ae5d73c05 4f7b22a0 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2026/09/04 02:30 upstream 8ab1afb2eb24 801f0966 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2026/08/30 11:16 upstream 08dbfad3f504 2f52988a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2026/08/29 08:45 upstream cf72cbb39da8 2f52988a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2026/08/28 04:58 upstream 818bebeb63dd e2fa417d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2026/08/27 12:50 upstream 818bebeb63dd c53a1b9c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in hfs_extend_file
2024/06/04 08:08 upstream 2ab795141095 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in hfs_extend_file
2024/06/21 20:55 upstream 66cc544fd75c c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in hfs_extend_file
2026/09/02 13:20 linux-next 8b72f6626dc3 85995287 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hfs_extend_file
2026/08/31 12:39 linux-next e30626823a40 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hfs_extend_file
2026/08/31 01:21 linux-next e30626823a40 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hfs_extend_file
2026/08/30 14:26 linux-next e30626823a40 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hfs_extend_file
2026/08/29 05:41 linux-next e30626823a40 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hfs_extend_file
2026/08/28 16:58 linux-next e30626823a40 bcbc8ceb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hfs_extend_file
2026/08/28 14:06 linux-next 3d83758432b5 bcbc8ceb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hfs_extend_file
2026/02/08 17:39 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 59e4d31a0470 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in hfs_extend_file
* Struck through repros no longer work on HEAD.