syzbot


WARNING in l2cap_unregister_user

Status: closed as invalid on 2026/01/13 16:48
Subsystems: bluetooth
[Documentation on labels]
First crash: 52d, last: 52d

Sample crash report:
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: kernel/locking/mutex.c:593 at 0x0, CPU#1: khidpd_00075504/6726
Modules linked in:
CPU: 1 UID: 0 PID: 6726 Comm: khidpd_00075504 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:593 [inline]
RIP: 0010:__mutex_lock+0x10dc/0x1350 kernel/locking/mutex.c:776
Code: 82 8f 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 48 02 00 00 83 3d 98 5d 25 04 00 75 13 48 8d 3d 5b 66 28 04 48 c7 c6 e0 19 6b 8b <67> 48 0f b9 3a 90 e9 6b f0 ff ff 90 0f 0b 90 e9 51 f4 ff ff 90 0f
RSP: 0018:ffffc9001b72fa20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc9001b72fb00 RCX: ffff888030c05b80
RDX: 0000000000000000 RSI: ffffffff8b6b19e0 RDI: ffffffff8f853c70
RBP: ffffc9001b72fbd0 R08: ffffffff8f8233a3 R09: 1ffffffff1f04674
R10: dffffc0000000000 R11: fffffbfff1f04675 R12: ffff88807de94058
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125f37000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc70fff4000 CR3: 0000000075eae000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 l2cap_unregister_user+0x6a/0x1b0 net/bluetooth/l2cap_core.c:1729
 hidp_session_thread+0x3a1/0x420 net/bluetooth/hidp/core.c:1304
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	48 c1 e8 03          	shr    $0x3,%rax
   4:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax
   9:	84 c0                	test   %al,%al
   b:	0f 85 48 02 00 00    	jne    0x259
  11:	83 3d 98 5d 25 04 00 	cmpl   $0x0,0x4255d98(%rip)        # 0x4255db0
  18:	75 13                	jne    0x2d
  1a:	48 8d 3d 5b 66 28 04 	lea    0x428665b(%rip),%rdi        # 0x428667c
  21:	48 c7 c6 e0 19 6b 8b 	mov    $0xffffffff8b6b19e0,%rsi
* 28:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2d:	90                   	nop
  2e:	e9 6b f0 ff ff       	jmp    0xfffff09e
  33:	90                   	nop
  34:	0f 0b                	ud2
  36:	90                   	nop
  37:	e9 51 f4 ff ff       	jmp    0xfffff48d
  3c:	90                   	nop
  3d:	0f                   	.byte 0xf

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/07 03:26 linux-next 6987d58a9cbc d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in l2cap_unregister_user
* Struck through repros no longer work on HEAD.