linux-kernel - Re: [syzbot] [bluetooth?] WARNING in hci_connect

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Message-ID: <697ebb99.a70a0220.2148d8.0008.GAE@google.com>
Date: Sat, 31 Jan 2026 18:34:01 -0800
From: syzbot <syzbot+5897b3c764f5989ea942@...kaller.appspotmail.com>
To: hdanton@...a.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] WARNING in hci_connect_sco

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in hci_conn_drop

------------[ cut here ]------------
workqueue: cannot queue hci_conn_timeout on wq hci0
WARNING: kernel/workqueue.c:2251 at __queue_work+0xcbb/0x10f0 kernel/workqueue.c:2250, CPU#0: syz.1.10090/27807
Modules linked in:
CPU: 0 UID: 0 PID: 27807 Comm: syz.1.10090 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
RIP: 0010:__queue_work+0xcbf/0x10f0 kernel/workqueue.c:2250
Code: 00 00 00 fc ff df 49 8d 94 24 78 01 00 00 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 15 04 00 00 48 8d 3d 95 e7 eb 0e 48 8b 75 18 <67> 48 0f b9 3a e9 77 f7 ff ff e8 a2 b0 38 00 90 0f 0b 90 e9 ff f5
RSP: 0018:ffffc9000351fbd0 EFLAGS: 00010046
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffff1100765514b
RDX: ffff88802a0ab178 RSI: ffffffff8a71aaf0 RDI: ffffffff90ba3240
RBP: ffff88803b2a8a40 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88802a0ab000
R13: ffff8880375b8000 R14: ffff88803b2a8a88 R15: ffff88803b2a8a48
FS:  00007f7ed548e6c0(0000) GS:ffff8880d65dc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7ed548dff8 CR3: 00000000568a8000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __queue_delayed_work+0x365/0x470 kernel/workqueue.c:2503
 queue_delayed_work_on+0x180/0x1e0 kernel/workqueue.c:2555
 queue_delayed_work include/linux/workqueue.h:684 [inline]
 hci_conn_drop.part.0+0x3c9/0x430 include/net/bluetooth/hci_core.h:1717
 hci_conn_drop include/net/bluetooth/hci_core.h:1688 [inline]
 hci_connect_sco+0x420/0x980 net/bluetooth/hci_conn.c:1767
 sco_connect net/bluetooth/sco.c:339 [inline]
 sco_sock_connect+0x303/0xac0 net/bluetooth/sco.c:665
 __sys_connect_file+0x141/0x1a0 net/socket.c:2089
 __sys_connect+0x141/0x170 net/socket.c:2108
 __do_sys_connect net/socket.c:2114 [inline]
 __se_sys_connect net/socket.c:2111 [inline]
 __x64_sys_connect+0x72/0xb0 net/socket.c:2111
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7ed459aeb9
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:00007f7ed548e028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f7ed4815fa0 RCX: 00007f7ed459aeb9
RDX: 0000000000000008 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007f7ed4608c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7ed4816038 R14: 00007f7ed4815fa0 R15: 00007ffdf46ed6a8
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 fc                	add    %bh,%ah
   4:	ff                   	lcall  (bad)
   5:	df 49 8d             	fisttps -0x73(%rcx)
   8:	94                   	xchg   %eax,%esp
   9:	24 78                	and    $0x78,%al
   b:	01 00                	add    %eax,(%rax)
   d:	00 48 89             	add    %cl,-0x77(%rax)
  10:	f9                   	stc
  11:	48 c1 e9 03          	shr    $0x3,%rcx
  15:	80 3c 01 00          	cmpb   $0x0,(%rcx,%rax,1)
  19:	0f 85 15 04 00 00    	jne    0x434
  1f:	48 8d 3d 95 e7 eb 0e 	lea    0xeebe795(%rip),%rdi        # 0xeebe7bb
  26:	48 8b 75 18          	mov    0x18(%rbp),%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 77 f7 ff ff       	jmp    0xfffff7ab
  34:	e8 a2 b0 38 00       	call   0x38b0db
  39:	90                   	nop
  3a:	0f 0b                	ud2
  3c:	90                   	nop
  3d:	e9                   	.byte 0xe9
  3e:	ff f5                	push   %rbp


Tested on:

commit:         162b4244 Merge tag 'iommu-fixes-v6.19-rc7' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=175ce45a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f1fac0919970b671
dashboard link: https://syzkaller.appspot.com/bug?extid=5897b3c764f5989ea942
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=122b972a580000