refcount_t: increment on 0; use-after-free.
WARNING: CPU: 1 PID: 13397 at lib/refcount.c:156 refcount_inc_checked lib/refcount.c:156 [inline]
WARNING: CPU: 1 PID: 13397 at lib/refcount.c:156 refcount_inc_checked+0x61/0x70 lib/refcount.c:154
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 13397 Comm: syz-executor.4 Not tainted 5.2.0-rc1+ #1
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+0x2cb/0x744 kernel/panic.c:219
 __warn.cold+0x20/0x4d kernel/panic.c:576
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:986
RIP: 0010:refcount_inc_checked lib/refcount.c:156 [inline]
RIP: 0010:refcount_inc_checked+0x61/0x70 lib/refcount.c:154
Code: 1d d0 97 48 06 31 ff 89 de e8 2b 80 3c fe 84 db 75 dd e8 e2 7e 3c fe 48 c7 c7 80 96 a4 87 c6 05 b0 97 48 06 01 e8 4d c4 0e fe <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41
RSP: 0018:ffff8880602978e8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000012473 RSI: ffffffff815ac7e6 RDI: ffffed100c052f0f
RBP: ffff8880602978f8 R08: ffff8880624e6340 R09: ffffed1015d26011
R10: ffffed1015d26010 R11: ffff8880ae930087 R12: ffff8880a75467b8
R13: ffff888095957620 R14: ffff888095957618 R15: ffff8880a7546738
 kref_get include/linux/kref.h:47 [inline]
 kobject_get+0x66/0xc0 lib/kobject.c:642
 kset_get include/linux/kobject.h:214 [inline]
 kobj_kset_join lib/kobject.c:194 [inline]
 kobject_add_internal lib/kobject.c:246 [inline]
 kobject_add_internal+0x14f/0x380 lib/kobject.c:225
 kobject_add_varg lib/kobject.c:390 [inline]
 kobject_add+0x150/0x1c0 lib/kobject.c:442
 class_dir_create_and_add drivers/base/core.c:1732 [inline]
 get_device_parent.isra.0+0x413/0x560 drivers/base/core.c:1787
 device_add+0x2df/0x17a0 drivers/base/core.c:2048
 hci_register_dev+0x2e8/0x860 net/bluetooth/hci_core.c:3305
 __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+0x2d0/0x470 drivers/bluetooth/hci_vhci.c:299
 call_write_iter include/linux/fs.h:1872 [inline]
 new_sync_write+0x4d3/0x770 fs/read_write.c:483
 __vfs_write+0xe1/0x110 fs/read_write.c:496
 vfs_write+0x20c/0x580 fs/read_write.c:558
 ksys_write+0x14f/0x290 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __ia32_sys_write+0x71/0xb0 fs/read_write.c:620
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xd7d arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f87849
Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5d830cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200000c0
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..