refcount_t: underflow; use-after-free.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 7729 at lib/refcount.c:187 refcount_sub_and_test lib/refcount.c:187 [inline]
WARNING: CPU: 1 PID: 7729 at lib/refcount.c:187 refcount_sub_and_test.cold+0x18/0x22 lib/refcount.c:177
Kernel panic - not syncing: panic_on_warn set ...

kobject: 'hci3': free name
CPU: 1 PID: 7729 Comm: syz-executor476 Not tainted 4.14.113 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x19c lib/dump_stack.c:53
 panic+0x1f2/0x438 kernel/panic.c:182
 __warn.cold+0x2f/0x34 kernel/panic.c:546
 report_bug+0x216/0x254 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x1bb/0x310 arch/x86/kernel/traps.c:295
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:944
RIP: 0010:refcount_sub_and_test lib/refcount.c:187 [inline]
RIP: 0010:refcount_sub_and_test.cold+0x18/0x22 lib/refcount.c:177
RSP: 0018:ffff8880a0177a68 EFLAGS: 00010286
RAX: 0000000000000026 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8880835b6a00 RDI: ffffed101402ef43
RBP: ffff8880a0177a90 R08: 0000000000000026 R09: ffff8880835b6a20
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88821a9f1078
R13: 0000000000000001 R14: 00000000ffffffff R15: ffff88821a9f0ff8
 refcount_dec_and_test+0x1b/0x20 lib/refcount.c:212
 kref_put include/linux/kref.h:69 [inline]
 kobject_put+0x60/0x80 lib/kobject.c:692
 kset_put include/linux/kobject.h:215 [inline]
 kobj_kset_leave+0x17f/0x220 lib/kobject.c:184
 kobject_del.part.0+0x79/0xf0 lib/kobject.c:579
 kobject_del+0x20/0x30 lib/kobject.c:571
 cleanup_glue_dir.part.0+0xd2/0x100 drivers/base/core.c:1581
 cleanup_glue_dir drivers/base/core.c:614 [inline]
 device_del+0x78e/0xaa0 drivers/base/core.c:2024
 hci_unregister_dev+0x298/0x7d0 net/bluetooth/hci_core.c:3212
 vhci_release+0x76/0xf0 drivers/bluetooth/hci_vhci.c:354
 __fput+0x277/0x7a0 fs/file_table.c:210
 ____fput+0x16/0x20 fs/file_table.c:244
 task_work_run+0x119/0x190 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x7df/0x2c10 kernel/exit.c:874
 do_group_exit+0x111/0x330 kernel/exit.c:977
 SYSC_exit_group kernel/exit.c:988 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:986
 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43fed8
RSP: 002b:00007ffd3b0ea108 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043fed8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf710 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..