bisecting fixing commit since 6a24ca2506d64598eac5d5219e99acca9bde4ca5
building syzkaller on 6436ce4bcd8e2c7dcca0b171ac91f51e96d973f8
testing commit 6a24ca2506d64598eac5d5219e99acca9bde4ca5 with gcc (GCC) 8.1.0
kernel signature: 8166fa5801e964a673c9312c2b145b5a61435803eb9633f06050a629d1f150ab
run #0: crashed: WARNING: ODEBUG bug in bt_host_release
run #1: crashed: WARNING: ODEBUG bug in bt_host_release
run #2: crashed: WARNING: ODEBUG bug in bt_host_release
run #3: crashed: general protection fault in __queue_work
run #4: crashed: general protection fault in __queue_work
run #5: crashed: WARNING: ODEBUG bug in bt_host_release
run #6: crashed: KASAN: use-after-free Read in __queue_work
run #7: crashed: WARNING: ODEBUG bug in bt_host_release
run #8: crashed: general protection fault in __queue_work
run #9: crashed: WARNING: ODEBUG bug in bt_host_release
testing current HEAD 5b7a52cd2eef952cee8a72512ef370bcdef46636
testing commit 5b7a52cd2eef952cee8a72512ef370bcdef46636 with gcc (GCC) 8.1.0
kernel signature: 8e8b80e89b2ddd3ceeec97e27167ca91ca0df188581eeb16820a335fb764f9cd
run #0: crashed: KASAN: use-after-free Read in __queue_work
run #1: crashed: general protection fault in __queue_work
run #2: crashed: WARNING: ODEBUG bug in bt_host_release
run #3: crashed: general protection fault in __queue_work
run #4: crashed: general protection fault in __queue_work
run #5: crashed: KASAN: use-after-free Read in __queue_work
run #6: crashed: general protection fault in __queue_work
run #7: crashed: KASAN: use-after-free Read in __queue_work
run #8: crashed: general protection fault in __queue_work
run #9: crashed: WARNING: ODEBUG bug in bt_host_release
revisions tested: 2, total time: 30m20.511061984s (build: 16m31.464367481s, test: 13m18.940687479s)
the crash still happens on HEAD
commit msg: Linux 4.14.202
crash: WARNING: ODEBUG bug in bt_host_release
Bluetooth: hci0 command 0x0c1a tx timeout
Bluetooth: hci3 command 0x041b tx timeout
Bluetooth: hci0 command 0x0c1a tx timeout
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x90 kernel/workqueue.c:4852
------------[ cut here ]------------
WARNING: CPU: 1 PID: 22879 at lib/debugobjects.c:290 debug_print_object.cold.8+0xa7/0xdb lib/debugobjects.c:287
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 22879 Comm: syz-executor.5 Not tainted 4.14.202-syzkaller #0
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+0x14b/0x1f1 lib/dump_stack.c:58
 panic+0x1b0/0x358 kernel/panic.c:183
 __warn.cold.7+0x25/0x2c kernel/panic.c:547
 report_bug+0x1a4/0x1f3 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 do_error_trap+0x1bd/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:964
RIP: 0010:debug_print_object.cold.8+0xa7/0xdb lib/debugobjects.c:287
RSP: 0018:ffff888093f77a38 EFLAGS: 00010082
RAX: 0000000000000061 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000061 RSI: ffffffff86cbea20 RDI: ffffed10127eef3e
RBP: ffff888093f77a60 R08: 0000000000000000 R09: 0000000000000000
R10: fffffbfff13444c9 R11: dffffc0000000000 R12: ffffffff86cb9ca0
R13: ffffffff813b12d0 R14: 0000000000000000 R15: dffffc0000000000
 __debug_check_no_obj_freed lib/debugobjects.c:747 [inline]
 debug_check_no_obj_freed+0x4bc/0x890 lib/debugobjects.c:776
 kfree+0xbd/0x270 mm/slab.c:3814
 bt_host_release+0x10/0x20 net/bluetooth/hci_sysfs.c:86
 device_release+0xd7/0x170 drivers/base/core.c:831
 kobject_cleanup lib/kobject.c:646 [inline]
 kobject_release lib/kobject.c:675 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x10d/0x1b0 lib/kobject.c:692
 put_device+0x12/0x20 drivers/base/core.c:2014
 hci_free_dev+0x10/0x20 net/bluetooth/hci_core.c:3065
 vhci_release+0x73/0xe0 drivers/bluetooth/hci_vhci.c:355
 __fput+0x232/0x740 fs/file_table.c:210
 ____fput+0x9/0x10 fs/file_table.c:244
 task_work_run+0xe5/0x170 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x953/0x2c40 kernel/exit.c:865
 do_group_exit+0xf8/0x2c0 kernel/exit.c:962
 SYSC_exit_group kernel/exit.c:973 [inline]
 SyS_exit_group+0x18/0x20 kernel/exit.c:971
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45d4d9
RSP: 002b:00007ffe22810408 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045d4d9
RDX: 0000000000416d61 RSI: 00000000016a85f0 RDI: 0000000000000043
RBP: 00000000004c306d R08: 000000000000000b R09: 0000000000000000
R10: 0000000001ffb940 R11: 0000000000000246 R12: 0000000000000007
R13: 00007ffe22810550 R14: 0000000000043f3c R15: 00007ffe22810560

======================================================