[syzbot] [net?] WARNING in hci_sock_sendmsg

[syzbot <syzbot+8fe47b0d0d2830a8d3be@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    9974969c1403 Add linux-next specific files for 20260428
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16056b6c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fff2b12da07ad
dashboard link: https://syzkaller.appspot.com/bug?extid=8fe47b0d0d2830a8d3be
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: https://storage.googleapis.com/syzbot-assets/755177aac4cc/disk-9974969c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fe2f57d4e79e/vmlinux-9974969c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/15b13a4a7518/bzImage-9974969c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8fe47b0d0d2830a8d3be@syzkaller.appspotmail.com

------------[ cut here ]------------
workqueue: cannot queue hci_tx_work on wq hci0
WARNING: kernel/workqueue.c:2298 at __queue_work+0xd67/0x1010 kernel/workqueue.c:2296, CPU#1: syz.0.23/5836
Modules linked in:
CPU: 1 UID: 0 PID: 5836 Comm: syz.0.23 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__queue_work+0xd87/0x1010 kernel/workqueue.c:2296
Code: 01 00 00 4c 8d 35 49 c5 21 0e 4c 89 e8 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ef e8 b3 f6 a0 00 49 8b 75 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 11 48
RSP: 0018:ffffc90005817958 EFLAGS: 00010046
RAX: 1ffff11004a2198f RBX: 0000000000000008 RCX: 0000000000080000
RDX: ffff888037302968 RSI: ffffffff8a252410 RDI: ffffffff8faf47a0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1004a2198d R12: dffffc0000000000
R13: ffff88802510cc78 R14: ffffffff8faf47a0 R15: ffff888037302968
FS:  00007f2b3bbfe6c0(0000) GS:ffff888125dd8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c459547 CR3: 000000004410a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 queue_work_on+0x106/0x1d0 kernel/workqueue.c:2432
 queue_work include/linux/workqueue.h:696 [inline]
 hci_sock_sendmsg+0xb3d/0xf40 net/bluetooth/hci_sock.c:-1
 sock_sendmsg_nosec+0x112/0x150 net/socket.c:797
 __sock_sendmsg net/socket.c:812 [inline]
 sock_write_iter+0x308/0x410 net/socket.c:1269
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x629/0xba0 fs/read_write.c:688
 ksys_write+0x156/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b3d9acdd9
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:00007f2b3bbfe028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2b3dc25fa0 RCX: 00007f2b3d9acdd9
RDX: 0000000000000006 RSI: 0000200000000240 RDI: 0000000000000006
RBP: 00007f2b3da42d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b3dc26038 R14: 00007f2b3dc25fa0 R15: 00007fffb59042a8
 </TASK>
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	00 00                	add    %al,(%rax)
   2:	4c 8d 35 49 c5 21 0e 	lea    0xe21c549(%rip),%r14        # 0xe21c552
   9:	4c 89 e8             	mov    %r13,%rax
   c:	48 c1 e8 03          	shr    $0x3,%rax
  10:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
  15:	74 08                	je     0x1f
  17:	4c 89 ef             	mov    %r13,%rdi
  1a:	e8 b3 f6 a0 00       	call   0xa0f6d2
  1f:	49 8b 75 00          	mov    0x0(%r13),%rsi
  23:	4c 89 f7             	mov    %r14,%rdi
  26:	4c 89 fa             	mov    %r15,%rdx
* 29:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2e:	48 83 c4 58          	add    $0x58,%rsp
  32:	5b                   	pop    %rbx
  33:	41 5c                	pop    %r12
  35:	41 5d                	pop    %r13
  37:	41 5e                	pop    %r14
  39:	41 5f                	pop    %r15
  3b:	5d                   	pop    %rbp
  3c:	e9                   	.byte 0xe9
  3d:	11                   	.byte 0x11
  3e:	48                   	rex.W


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