------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at 0x0, CPU#1: kbnepd bnep0/8407
Modules linked in:
CPU: 1 UID: 0 PID: 8407 Comm: kbnepd bnep0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: 74 26 00 0b 67 48 0f b9 3a eb 4a e8 d8 d2 36 fd 48 8d 3d 71 26 00 0b 67 48 0f b9 3a eb 37 e8 c5 d2 36 fd 48 8d 3d 6e 26 00 0b <67> 48 0f b9 3a eb 24 e8 b2 d2 36 fd 48 8d 3d 6b 26 00 0b 67 48 0f
RSP: 0018:ffffc90005497700 EFLAGS: 00010293
RAX: ffffffff848a779b RBX: 0000000000000003 RCX: ffff8880441edb80
RDX: 0000000000000000 RSI: ffffffff8e67b660 RDI: ffffffff8f8a9e10
RBP: 0000000000000000 R08: ffff8880441edb80 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8880556ca860 R14: ffff8880556ca878 R15: ffffffff85c80520
FS:  0000000000000000(0000) GS:ffff8881261b1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5fe3f156c0 CR3: 00000000331f6000 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+0x280/0x8e0 drivers/base/core.c:3855
 unregister_netdevice_many_notify+0x1da6/0x2310 net/core/dev.c:12416
 unregister_netdevice_many net/core/dev.c:12444 [inline]
 unregister_netdevice_queue net/core/dev.c:12258 [inline]
 unregister_netdevice include/linux/netdevice.h:3405 [inline]
 unregister_netdev+0x157/0x1f0 net/core/dev.c:12462
 bnep_session+0x294d/0x2b40 net/bluetooth/bnep/core.c:525
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess):
   0:	74 26                	je     0x28
   2:	00 0b                	add    %cl,(%rbx)
   4:	67 48 0f b9 3a       	ud1    (%edx),%rdi
   9:	eb 4a                	jmp    0x55
   b:	e8 d8 d2 36 fd       	call   0xfd36d2e8
  10:	48 8d 3d 71 26 00 0b 	lea    0xb002671(%rip),%rdi        # 0xb002688
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 37                	jmp    0x55
  1e:	e8 c5 d2 36 fd       	call   0xfd36d2e8
  23:	48 8d 3d 6e 26 00 0b 	lea    0xb00266e(%rip),%rdi        # 0xb002698
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 24                	jmp    0x55
  31:	e8 b2 d2 36 fd       	call   0xfd36d2e8
  36:	48 8d 3d 6b 26 00 0b 	lea    0xb00266b(%rip),%rdi        # 0xb0026a8
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf