[syzbot] [bluetooth?] WARNING in hci_send_cmd (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5ce74bc1b7cb Add linux-next specific files for 20251211
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14b0261a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a94030c847137a18
dashboard link: https://syzkaller.appspot.com/bug?extid=de67f74f87a8fd41bd70
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e1660176a50f/disk-5ce74bc1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/616ede012bbd/vmlinux-5ce74bc1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c0c5bc40fd8/bzImage-5ce74bc1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+de67f7...@syzkaller.appspotmail.com

Bluetooth: MGMT ver 1.23
------------[ cut here ]------------
workqueue: cannot queue hci_cmd_work on wq hci0
WARNING: kernel/workqueue.c:2271 at __queue_work+0xd20/0xf90 kernel/workqueue.c:2269, CPU#1: syz.6.1277/11092
Modules linked in:
CPU: 1 UID: 0 PID: 11092 Comm: syz.6.1277 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:__queue_work+0xd4b/0xf90 kernel/workqueue.c:2269
Code: 83 c5 18 4c 89 e8 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ef e8 e6 68 9d 00 49 8b 75 00 49 81 c7 78 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 e9 3d 2a
RSP: 0018:ffffc900030d76d0 EFLAGS: 00010086
RAX: 1ffff1100afba184 RBX: 0000000000000008 RCX: 0000000000080000
RDX: ffff88807d99d178 RSI: ffffffff8a5590f0 RDI: ffffffff8f851310
RBP: 0000000000000000 R08: ffff888057dd0c0f R09: 1ffff1100afba181
R10: dffffc0000000000 R11: ffffed100afba182 R12: dffffc0000000000
R13: ffff888057dd0c20 R14: ffffffff8f851310 R15: ffff88807d99d178
FS: 00007fefeae826c0(0000) GS:ffff888125f32000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fefeae60f98 CR3: 0000000066f94000 CR4: 00000000003526f0
Call Trace:
<TASK>
queue_work_on+0x181/0x270 kernel/workqueue.c:2405
queue_work include/linux/workqueue.h:669 [inline]
hci_send_cmd+0xb7/0x1b0 net/bluetooth/hci_core.c:3110
set_link_security+0x588/0x740 net/bluetooth/mgmt.c:1934
hci_mgmt_cmd+0xa14/0xfa0 net/bluetooth/hci_sock.c:1721
hci_sock_sendmsg+0x6d7/0xf30 net/bluetooth/hci_sock.c:1841
sock_sendmsg_nosec+0x18f/0x1d0 net/socket.c:737
__sock_sendmsg net/socket.c:752 [inline]
sock_write_iter+0x2d9/0x3d0 net/socket.c:1210
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5c9/0xb30 fs/read_write.c:686
ksys_write+0x145/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fefe9f8f749
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:00007fefeae82038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fefea1e5fa0 RCX: 00007fefe9f8f749
RDX: 0000000000000007 RSI: 0000200000000000 RDI: 0000000000000007
RBP: 00007fefea013f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fefea1e6038 R14: 00007fefea1e5fa0 R15: 00007fff2736b578
</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 e6 68 9d 00 call 0x9d68ff
19: 49 8b 75 00 mov 0x0(%r13),%rsi
1d: 49 81 c7 78 01 00 00 add $0x178,%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: e9 .byte 0xe9
3e: 3d .byte 0x3d
3f: 2a .byte 0x2a


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup