------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#1: kbnepd bnep0/16394
Modules linked in:
CPU: 1 UID: 0 PID: 16394 Comm: kbnepd bnep0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: 54 b2 8e 0b 67 48 0f b9 3a eb 4a e8 b8 21 f3 fc 48 8d 3d 51 b2 8e 0b 67 48 0f b9 3a eb 37 e8 a5 21 f3 fc 48 8d 3d 4e b2 8e 0b <67> 48 0f b9 3a eb 24 e8 92 21 f3 fc 48 8d 3d 4b b2 8e 0b 67 48 0f
RSP: 0018:ffffc900033bf7e0 EFLAGS: 00010293
RAX: ffffffff84d3f25b RBX: 0000000000000003 RCX: ffff88801eba0000
RDX: 0000000000000000 RSI: ffffffff8f3652c0 RDI: ffffffff9062a4b0
RBP: 0000000000000000 R08: ffff88801eba0000 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff88807b68b460 R14: ffff88807b68b478 R15: ffffffff8626e180
FS:  0000000000000000(0000) GS:ffff88812504f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7b1e3f14b8 CR3: 000000000e946000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __refcount_sub_and_test include/linux/refcount.h:400 [inline]
 __refcount_dec_and_test include/linux/refcount.h:432 [inline]
 refcount_dec_and_test include/linux/refcount.h:450 [inline]
 kref_put include/linux/kref.h:64 [inline]
 klist_dec_and_del+0x3c7/0x3d0 lib/klist.c:206
 klist_put lib/klist.c:217 [inline]
 klist_del+0xa6/0x110 lib/klist.c:230
 device_del+0x27f/0x8f0 drivers/base/core.c:3938
 unregister_netdevice_many_notify+0x1be4/0x2150 net/core/dev.c:12496
 unregister_netdevice_many net/core/dev.c:12534 [inline]
 unregister_netdevice_queue net/core/dev.c:12336 [inline]
 unregister_netdevice include/linux/netdevice.h:3477 [inline]
 unregister_netdev+0x155/0x1f0 net/core/dev.c:12642
 bnep_session+0x2af2/0x2d20 net/bluetooth/bnep/core.c:544
 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:	54                   	push   %rsp
   1:	b2 8e                	mov    $0x8e,%dl
   3:	0b 67 48             	or     0x48(%rdi),%esp
   6:	0f b9 3a             	ud1    (%rdx),%edi
   9:	eb 4a                	jmp    0x55
   b:	e8 b8 21 f3 fc       	call   0xfcf321c8
  10:	48 8d 3d 51 b2 8e 0b 	lea    0xb8eb251(%rip),%rdi        # 0xb8eb268
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 37                	jmp    0x55
  1e:	e8 a5 21 f3 fc       	call   0xfcf321c8
  23:	48 8d 3d 4e b2 8e 0b 	lea    0xb8eb24e(%rip),%rdi        # 0xb8eb278
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 24                	jmp    0x55
  31:	e8 92 21 f3 fc       	call   0xfcf321c8
  36:	48 8d 3d 4b b2 8e 0b 	lea    0xb8eb24b(%rip),%rdi        # 0xb8eb288
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf