------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 10490 at lib/refcount.c:28 refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 1 UID: 0 PID: 10490 Comm: kbnepd bnep0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Code: 20 55 be 8b e8 77 b9 f9 fc 90 0f 0b 90 90 eb d7 e8 db 9c 36 fd c6 05 4e 87 dd 0a 01 90 48 c7 c7 80 55 be 8b e8 57 b9 f9 fc 90 <0f> 0b 90 90 eb b7 e8 bb 9c 36 fd c6 05 2b 87 dd 0a 01 90 48 c7 c7
RSP: 0018:ffffc9001bdbf6e0 EFLAGS: 00010246
RAX: da603683fe06f600 RBX: 0000000000000003 RCX: ffff888032168000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000000 R08: ffff8880b8924293 R09: 1ffff11017124852
R10: dffffc0000000000 R11: ffffed1017124853 R12: dffffc0000000000
R13: ffff88805aadec60 R14: ffff88805aadec78 R15: ffffffff85c63270
FS:  0000000000000000(0000) GS:ffff88812623e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f884ad156c0 CR3: 000000002738a000 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+0x1df2/0x2390 net/core/dev.c:12319
 unregister_netdevice_many net/core/dev.c:12347 [inline]
 unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12161
 unregister_netdevice include/linux/netdevice.h:3389 [inline]
 unregister_netdev+0x1f/0x60 net/core/dev.c:12365
 bnep_session+0x294d/0x2b40 net/bluetooth/bnep/core.c:525
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>