------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 1 PID: 1446 at lib/refcount.c:153 refcount_inc_checked /lib/refcount.c:153 [inline]
WARNING: CPU: 1 PID: 1446 at lib/refcount.c:153 refcount_inc_checked+0x61/0x70 /lib/refcount.c:151
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 1446 Comm: syz-executor.4 Not tainted 4.19.59 #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack /lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 /lib/dump_stack.c:113
 panic+0x263/0x507 /kernel/panic.c:185
 __warn.cold+0x20/0x4a /kernel/panic.c:540
 report_bug+0x263/0x2b0 /lib/bug.c:186
 fixup_bug /arch/x86/kernel/traps.c:178 [inline]
 fixup_bug /arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x204/0x360 /arch/x86/kernel/traps.c:296
kobject: 'loop2' (00000000306d4d0d): kobject_uevent_env
 do_invalid_op+0x1b/0x20 /arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 /arch/x86/entry/entry_64.S:1013
RIP: 0010:refcount_inc_checked /lib/refcount.c:153 [inline]
RIP: 0010:refcount_inc_checked+0x61/0x70 /lib/refcount.c:151
Code: 1d 8e e9 12 06 31 ff 89 de e8 bb 86 47 fe 84 db 75 dd e8 72 85 47 fe 48 c7 c7 80 96 81 87 c6 05 6e e9 12 06 01 e8 8d 5f 1b fe <0f> 0b eb c1 90 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 41
kobject: 'loop2' (00000000306d4d0d): fill_kobj_path: path = '/devices/virtual/block/loop2'
RSP: 0018:ffff88805c05f920 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000010e6e RSI: ffffffff8155b0b6 RDI: ffffed100b80bf16
RBP: ffff88805c05f930 R08: ffff888055d9c000 R09: ffffed1015d25079
R10: ffffed1015d25078 R11: ffff8880ae9283c7 R12: ffff8880a7f5f538
R13: ffff8880774aeea0 R14: ffff8880774aee98 R15: ffff8880a7f5f4b8
 kref_get /./include/linux/kref.h:47 [inline]
 kobject_get+0x66/0xc0 /lib/kobject.c:613
 kset_get /./include/linux/kobject.h:213 [inline]
 kobj_kset_join /lib/kobject.c:186 [inline]
 kobject_add_internal /lib/kobject.c:238 [inline]
 kobject_add_internal+0x14f/0x380 /lib/kobject.c:217
 kobject_add_varg /lib/kobject.c:382 [inline]
 kobject_add+0x150/0x1c0 /lib/kobject.c:426
kobject: 'loop5' (0000000068697f43): kobject_uevent_env
kobject: 'loop5' (0000000068697f43): fill_kobj_path: path = '/devices/virtual/block/loop5'
 class_dir_create_and_add /drivers/base/core.c:1560 [inline]
 get_device_parent.isra.0+0x415/0x570 /drivers/base/core.c:1615
 device_add+0x2f4/0x1760 /drivers/base/core.c:1871
 hci_register_dev+0x304/0x880 /net/bluetooth/hci_core.c:3198
 __vhci_create_device+0x2d0/0x5a0 /drivers/bluetooth/hci_vhci.c:139
 vhci_create_device /drivers/bluetooth/hci_vhci.c:163 [inline]
 vhci_get_user /drivers/bluetooth/hci_vhci.c:219 [inline]
 vhci_write+0x2d6/0x470 /drivers/bluetooth/hci_vhci.c:299
 call_write_iter /./include/linux/fs.h:1820 [inline]
 new_sync_write /fs/read_write.c:474 [inline]
 __vfs_write+0x587/0x810 /fs/read_write.c:487
 vfs_write+0x20c/0x560 /fs/read_write.c:549
 ksys_write+0x14f/0x2d0 /fs/read_write.c:599
 __do_sys_write /fs/read_write.c:611 [inline]
 __se_sys_write /fs/read_write.c:608 [inline]
 __x64_sys_write+0x73/0xb0 /fs/read_write.c:608
 do_syscall_64+0xfd/0x620 /arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459819
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fa84e4afc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459819
RDX: 0000000000000002 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa84e4b06d4
R13: 00000000004c9985 R14: 00000000004e0e40 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..