[syzbot] [bluetooth?] WARNING in hci_connect_sco

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d8ba32c5a460 Merge tag 'block-6.19-20251218' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=179a83c2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=513255d80ab78f2b
dashboard link: https://syzkaller.appspot.com/bug?extid=5897b3c764f5989ea942
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 (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d8ba32c5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ce9be55c4ca6/vmlinux-d8ba32c5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0a47a6667df3/bzImage-d8ba32c5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5897b3...@syzkaller.appspotmail.com

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workqueue: cannot queue hci_conn_timeout on wq hci0
WARNING: kernel/workqueue.c:2252 at __queue_work+0xd20/0xf90 kernel/workqueue.c:2250, CPU#0: syz.0.0/5341
Modules linked in:
CPU: 0 UID: 0 PID: 5341 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__queue_work+0xd4b/0xf90 kernel/workqueue.c:2250
Code: 83 c5 18 4c 89 e8 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ef e8 86 f8 9e 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 8d fb
RSP: 0018:ffffc9000bd4fb10 EFLAGS: 00010086
RAX: 1ffff11006c5114b RBX: 0000000000000008 RCX: 0000000000100000
RDX: ffff88801168a178 RSI: ffffffff8a596e20 RDI: ffffffff8fa52910
RBP: 0000000000000000 R08: ffff888036288a47 R09: 1ffff11006c51148
R10: dffffc0000000000 R11: ffffed1006c51149 R12: dffffc0000000000
R13: ffff888036288a58 R14: ffffffff8fa52910 R15: ffff88801168a178
FS: 00007f3f80e366c0(0000) GS:ffff88808d22a000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff38bb2f52 CR3: 00000000419d7000 CR4: 0000000000352ef0
Call Trace:
<TASK>
queue_delayed_work_on+0x18b/0x280 kernel/workqueue.c:2555
hci_connect_sco+0xe9/0x3a0 net/bluetooth/hci_conn.c:1767
sco_connect net/bluetooth/sco.c:339 [inline]
sco_sock_connect+0x308/0xad0 net/bluetooth/sco.c:665
__sys_connect_file net/socket.c:2089 [inline]
__sys_connect+0x316/0x440 net/socket.c:2108
__do_sys_connect net/socket.c:2114 [inline]
__se_sys_connect net/socket.c:2111 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2111
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: 0033:0x7f3f7ff8f7c9
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:00007f3f80e36038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f3f801e6090 RCX: 00007f3f7ff8f7c9
RDX: 0000000000000008 RSI: 0000200000000100 RDI: 0000000000000006
RBP: 00007f3f80013f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3f801e6128 R14: 00007f3f801e6090 R15: 00007ffdb2852538
</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 86 f8 9e 00 call 0x9ef89f
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: 8d (bad)
3f: fb sti


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