WARNING in lookup_open

Status: moderation: reported on 2026/08/23 11:06
Subsystems: fs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+f25044e41e8b70712db9@syzkaller.appspotmail.com
First crash: 7d03h, last: 1d17h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
887a3117 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in lookup_open 2026/08/21 00:35 2026/08/21 00:35 2026/08/21 01:24 1e72964b

Sample crash report:
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current)
WARNING: kernel/locking/rtmutex_common.h:193 at debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:193 [inline], CPU#1: syz.1.166/6892
WARNING: kernel/locking/rtmutex_common.h:193 at rt_mutex_slowunlock+0x734/0xa30 kernel/locking/rtmutex.c:1432, CPU#1: syz.1.166/6892
Modules linked in:
CPU: 1 UID: 0 PID: 6892 Comm: syz.1.166 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:193 [inline]
RIP: 0010:rt_mutex_slowunlock+0x73b/0xa30 kernel/locking/rtmutex.c:1432
Code: b1 8f 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 cf 02 00 00 83 3d 99 8f 5d 04 00 75 13 48 8d 3d 5c 7c 60 04 48 c7 c6 20 18 6d 8b <67> 48 0f b9 3a 90 e9 cf f9 ff ff 48 8d 3d 53 7c 60 04 67 48 0f b9
RSP: 0018:ffffc900067378a0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff888043829300 RCX: 0000000000080000
RDX: ffffc90006e21000 RSI: ffffffff8b6d1820 RDI: ffffffff8fb4ac50
RBP: ffffc90006737990 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f637f1 R12: dffffc0000000000
R13: 1ffff92000ce6f1c R14: ffff8880438292b0 R15: 0000000000000246
FS:  00007fe5029966c0(0000) GS:ffff888125cea000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c364fa2 CR3: 000000003ec9e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 inode_unlock include/linux/fs.h:1035 [inline]
 lookup_open+0x10bb/0x1a60 fs/namei.c:4578
 open_last_lookups fs/namei.c:4767 [inline]
 path_openat+0x67c/0x1d60 fs/namei.c:4997
 do_file_open+0x23e/0x4a0 fs/namei.c:5029
 do_sys_openat2+0x115/0x200 fs/open.c:1417
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1434
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe50473e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe502996028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe5049c5fa0 RCX: 00007fe50473e0d9
RDX: 0000000000000042 RSI: 0000200000001200 RDI: ffffffffffffff9c
RBP: 00007fe5047d5024 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000001ff R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe5049c6038 R14: 00007fe5049c5fa0 R15: 00007ffe67197148
 </TASK>
----------------
Code disassembly (best guess):
   0:	b1 8f                	mov    $0x8f,%cl
   2:	48 c1 e8 03          	shr    $0x3,%rax
   6:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax
   b:	84 c0                	test   %al,%al
   d:	0f 85 cf 02 00 00    	jne    0x2e2
  13:	83 3d 99 8f 5d 04 00 	cmpl   $0x0,0x45d8f99(%rip)        # 0x45d8fb3
  1a:	75 13                	jne    0x2f
  1c:	48 8d 3d 5c 7c 60 04 	lea    0x4607c5c(%rip),%rdi        # 0x4607c7f
  23:	48 c7 c6 20 18 6d 8b 	mov    $0xffffffff8b6d1820,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	90                   	nop
  30:	e9 cf f9 ff ff       	jmp    0xfffffa04
  35:	48 8d 3d 53 7c 60 04 	lea    0x4607c53(%rip),%rdi        # 0x4607c8f
  3c:	67                   	addr32
  3d:	48                   	rex.W
  3e:	0f                   	.byte 0xf
  3f:	b9                   	.byte 0xb9

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/24 20:33 upstream 0a0d1d55dad5 b55bd4c3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in lookup_open
2026/08/21 05:37 upstream 9d2ed026f031 1e72964b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_open
2026/08/19 10:56 upstream b126f6f5940f 1e72964b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_open
* Struck through repros no longer work on HEAD.