------------[ 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 bnep0/4115
Modules linked in:
CPU: 1 UID: 0 PID: 4115 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: d4 91 fe 0a 67 48 0f b9 3a eb 4a e8 c8 0c 33 fd 48 8d 3d d1 91 fe 0a 67 48 0f b9 3a eb 37 e8 b5 0c 33 fd 48 8d 3d ce 91 fe 0a <67> 48 0f b9 3a eb 24 e8 a2 0c 33 fd 48 8d 3d cb 91 fe 0a 67 48 0f
RSP: 0018:ffffc9000bc67740 EFLAGS: 00010293
RAX: ffffffff848deb0b RBX: 0000000000000003 RCX: ffff88802beb3d00
RDX: 0000000000000000 RSI: ffffffff8e68e200 RDI: ffffffff8f8c7ce0
RBP: 0000000000000000 R08: ffff88802beb3d00 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff88807de42c60 R14: ffff88807de42c78 R15: ffffffff85cec840
FS:  0000000000000000(0000) GS:ffff888125f1f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555568844588 CR3: 0000000032ab8000 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+0x1ddd/0x2340 net/core/dev.c:12418
 unregister_netdevice_many net/core/dev.c:12446 [inline]
 unregister_netdevice_queue net/core/dev.c:12260 [inline]
 unregister_netdevice include/linux/netdevice.h:3405 [inline]
 unregister_netdev+0x157/0x1f0 net/core/dev.c:12464
 bnep_session+0x29a5/0x2bd0 net/bluetooth/bnep/core.c:525
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	91                   	xchg   %eax,%ecx
   1:	fe 0a                	decb   (%rdx)
   3:	67 48 0f b9 3a       	ud1    (%edx),%rdi
   8:	eb 4a                	jmp    0x54
   a:	e8 c8 0c 33 fd       	call   0xfd330cd7
   f:	48 8d 3d d1 91 fe 0a 	lea    0xafe91d1(%rip),%rdi        # 0xafe91e7
  16:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1b:	eb 37                	jmp    0x54
  1d:	e8 b5 0c 33 fd       	call   0xfd330cd7
  22:	48 8d 3d ce 91 fe 0a 	lea    0xafe91ce(%rip),%rdi        # 0xafe91f7
* 29:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2e:	eb 24                	jmp    0x54
  30:	e8 a2 0c 33 fd       	call   0xfd330cd7
  35:	48 8d 3d cb 91 fe 0a 	lea    0xafe91cb(%rip),%rdi        # 0xafe9207
  3c:	67                   	addr32
  3d:	48                   	rex.W
  3e:	0f                   	.byte 0xf