[syzbot] [bluetooth?] WARNING in hci_send_cmd (4)

[syzbot <syzbot+00f5a866124dc44cce14@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    b4e07588e743 tracing: tell git to ignore the generated 'un..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1768ac36580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f17ac3d4b47ac43a
dashboard link: https://syzkaller.appspot.com/bug?extid=00f5a866124dc44cce14
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-b4e07588.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a3832abcd2f7/vmlinux-b4e07588.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0b5d6e6e9cbd/bzImage-b4e07588.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+00f5a866124dc44cce14@syzkaller.appspotmail.com

workqueue: cannot queue hci_cmd_work on wq hci0
WARNING: kernel/workqueue.c:2298 at __queue_work+0xd1f/0xfc0 kernel/workqueue.c:2296, CPU#0: kworker/0:3/1378
Modules linked in:
CPU: 0 UID: 0 PID: 1378 Comm: kworker/0:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events l2cap_info_timeout
RIP: 0010:__queue_work+0xd4a/0xfc0 kernel/workqueue.c:2296
Code: 83 c5 18 4c 89 e8 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ef e8 17 4d a5 00 49 8b 75 00 49 81 c7 70 01 00 00 4c 89 f7 4c 89 fa <67> 48 0f b9 3a 48 83 c4 58 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc
RSP: 0018:ffffc9000257f720 EFLAGS: 00010082
RAX: 1ffff110081cc181 RBX: 0000000000000008 RCX: ffff888000260000
RDX: ffff888040182170 RSI: ffffffff8aa9ccd0 RDI: ffffffff90368d70
RBP: 0000000000000020 R08: ffff888040e60bf7 R09: 1ffff110081cc17e
R10: dffffc0000000000 R11: ffffed10081cc17f R12: dffffc0000000000
R13: ffff888040e60c08 R14: ffffffff90368d70 R15: ffff888040182170
FS:  0000000000000000(0000) GS:ffff88808c80c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000005dc0 CR3: 0000000012a31000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 queue_work_on+0x106/0x1d0 kernel/workqueue.c:2432
 queue_work include/linux/workqueue.h:696 [inline]
 hci_send_cmd+0xb7/0x1a0 net/bluetooth/hci_core.c:3111
 hci_conn_auth net/bluetooth/hci_conn.c:2459 [inline]
 hci_conn_security+0x599/0xa80 net/bluetooth/hci_conn.c:2551
 l2cap_conn_start+0x3bc/0xf20 net/bluetooth/l2cap_core.c:1534
 l2cap_info_timeout+0x68/0xa0 net/bluetooth/l2cap_core.c:1685
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	83 c5 18             	add    $0x18,%ebp
   3:	4c 89 e8             	mov    %r13,%rax
   6:	48 c1 e8 03          	shr    $0x3,%rax
   a:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
   f:	74 08                	je     0x19
  11:	4c 89 ef             	mov    %r13,%rdi
  14:	e8 17 4d a5 00       	call   0xa54d30
  19:	49 8b 75 00          	mov    0x0(%r13),%rsi
  1d:	49 81 c7 70 01 00 00 	add    $0x170,%r15
  24:	4c 89 f7             	mov    %r14,%rdi
  27:	4c 89 fa             	mov    %r15,%rdx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	48 83 c4 58          	add    $0x58,%rsp
  33:	5b                   	pop    %rbx
  34:	41 5c                	pop    %r12
  36:	41 5d                	pop    %r13
  38:	41 5e                	pop    %r14
  3a:	41 5f                	pop    %r15
  3c:	5d                   	pop    %rbp
  3d:	c3                   	ret
  3e:	cc                   	int3
  3f:	cc                   	int3


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