------------[ 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 bnep0/9334
Modules linked in:
CPU: 0 UID: 0 PID: 9334 Comm: kbnepd bnep0 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: 84 ee 0d 0b 67 48 0f b9 3a eb 4a e8 48 3b f8 fc 48 8d 3d 81 ee 0d 0b 67 48 0f b9 3a eb 37 e8 35 3b f8 fc 48 8d 3d 7e ee 0d 0b <67> 48 0f b9 3a eb 24 e8 22 3b f8 fc 48 8d 3d 7b ee 0d 0b 67 48 0f
RSP: 0018:ffffc90005a777e0 EFLAGS: 00010293
RAX: ffffffff84cd687b RBX: 0000000000000003 RCX: ffff8880304c3e80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8fdb5700
RBP: 0000000000000000 R08: ffff8880304c3e80 R09: 0000000000000005
R10: 0000000000000100 R11: 0000000000000004 R12: dffffc0000000000
R13: ffff88804f49b8a0 R14: ffff88804f49b8b8 R15: ffffffff85a86840
FS:  0000000000000000(0000) GS:ffff8881259f2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe87a7ef70 CR3: 0000000077a78000 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+0xac/0x110 lib/klist.c:230
 device_del+0x280/0x8f0 drivers/base/core.c:3938
 unregister_netdevice_many_notify+0x1bb1/0x2120 net/core/dev.c:12515
 unregister_netdevice_many net/core/dev.c:12553 [inline]
 unregister_netdevice_queue net/core/dev.c:12355 [inline]
 unregister_netdevice include/linux/netdevice.h:3483 [inline]
 unregister_netdev+0x155/0x1f0 net/core/dev.c:12661
 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:	84 ee                	test   %ch,%dh
   2:	0d 0b 67 48 0f       	or     $0xf48670b,%eax
   7:	b9 3a eb 4a e8       	mov    $0xe84aeb3a,%ecx
   c:	48 3b f8             	cmp    %rax,%rdi
   f:	fc                   	cld
  10:	48 8d 3d 81 ee 0d 0b 	lea    0xb0dee81(%rip),%rdi        # 0xb0dee98
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 37                	jmp    0x55
  1e:	e8 35 3b f8 fc       	call   0xfcf83b58
  23:	48 8d 3d 7e ee 0d 0b 	lea    0xb0dee7e(%rip),%rdi        # 0xb0deea8
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 24                	jmp    0x55
  31:	e8 22 3b f8 fc       	call   0xfcf83b58
  36:	48 8d 3d 7b ee 0d 0b 	lea    0xb0dee7b(%rip),%rdi        # 0xb0deeb8
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf