------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: kbnepd bnep0/15559
Modules linked in:
CPU: 0 UID: 0 PID: 15559 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: 04 84 fe 0a 67 48 0f b9 3a eb 4a e8 a8 fd 32 fd 48 8d 3d 01 84 fe 0a 67 48 0f b9 3a eb 37 e8 95 fd 32 fd 48 8d 3d fe 83 fe 0a <67> 48 0f b9 3a eb 24 e8 82 fd 32 fd 48 8d 3d fb 83 fe 0a 67 48 0f
RSP: 0018:ffffc90004fd7740 EFLAGS: 00010293
RAX: ffffffff848dfa2b RBX: 0000000000000003 RCX: ffff88807c4b8000
RDX: 0000000000000000 RSI: ffffffff8e68e140 RDI: ffffffff8f8c7e30
RBP: 0000000000000000 R08: ffff88807c4b8000 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff88806c51ec60 R14: ffff88806c51ec78 R15: ffffffff85ced650
FS:  0000000000000000(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4d401e7dac CR3: 0000000051762000 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:12417
 unregister_netdevice_many net/core/dev.c:12445 [inline]
 unregister_netdevice_queue net/core/dev.c:12259 [inline]
 unregister_netdevice include/linux/netdevice.h:3405 [inline]
 unregister_netdev+0x157/0x1f0 net/core/dev.c:12463
 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):
   0:	04 84                	add    $0x84,%al
   2:	fe 0a                	decb   (%rdx)
   4:	67 48 0f b9 3a       	ud1    (%edx),%rdi
   9:	eb 4a                	jmp    0x55
   b:	e8 a8 fd 32 fd       	call   0xfd32fdb8
  10:	48 8d 3d 01 84 fe 0a 	lea    0xafe8401(%rip),%rdi        # 0xafe8418
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 37                	jmp    0x55
  1e:	e8 95 fd 32 fd       	call   0xfd32fdb8
  23:	48 8d 3d fe 83 fe 0a 	lea    0xafe83fe(%rip),%rdi        # 0xafe8428
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 24                	jmp    0x55
  31:	e8 82 fd 32 fd       	call   0xfd32fdb8
  36:	48 8d 3d fb 83 fe 0a 	lea    0xafe83fb(%rip),%rdi        # 0xafe8438
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf