bisecting fixing commit since 84f5ad468100f86d70096799e4ee716a17c2962f
building syzkaller on ddc3e85997efdad885e208db6a98bca86e5dd52f
testing commit 84f5ad468100f86d70096799e4ee716a17c2962f with gcc (GCC) 8.1.0
kernel signature: ec04085ae9dbd48193616d022f2645f0587ab136b5ee0cf7a0a3d57f038146be
all runs: crashed: WARNING: ODEBUG bug in rfcomm_dlc_free
testing current HEAD e0f8b8a65a473a8baa439cf865a694bbeb83fe90
testing commit e0f8b8a65a473a8baa439cf865a694bbeb83fe90 with gcc (GCC) 8.1.0
kernel signature: 8fe0e9e1c7194a618d3bc3defffd7c91f8d25ec730e3e723d895dea0e4f04980
all runs: crashed: WARNING: ODEBUG bug in rfcomm_dlc_free
revisions tested: 2, total time: 23m40.684958942s (build: 16m44.941617525s, test: 6m25.380662729s)
the crash still happens on HEAD
commit msg: Linux 4.14.170
crash: WARNING: ODEBUG bug in rfcomm_dlc_free
IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
ODEBUG: free active (active state 0) object type: timer_list hint: rfcomm_dlc_timeout+0x0/0x50 net/bluetooth/rfcomm/core.c:697
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7755 at lib/debugobjects.c:290 debug_print_object.cold.13+0xa7/0xdb lib/debugobjects.c:287
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7755 Comm: syz-executor.2 Not tainted 4.14.170-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+0xf7/0x13b lib/dump_stack.c:58
 panic+0x1b0/0x358 kernel/panic.c:183
 __warn.cold.8+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:963
RIP: 0010:debug_print_object.cold.13+0xa7/0xdb lib/debugobjects.c:287
RSP: 0018:ffff88809174fa70 EFLAGS: 00010082
RAX: 000000000000005e RBX: 0000000000000003 RCX: 0000000000000000
RDX: 000000000000005e RSI: ffffffff86cc2b20 RDI: ffffed10122e9f45
RBP: ffff88809174fa98 R08: 0000000000000000 R09: 0000000000000000
R10: fffffbfff1345309 R11: dffffc0000000000 R12: ffffffff86cbdd60
R13: ffffffff85d24dc0 R14: 0000000000000000 R15: ffff88808f1d1868
 __debug_check_no_obj_freed lib/debugobjects.c:747 [inline]
 debug_check_no_obj_freed+0x506/0x930 lib/debugobjects.c:776
 kfree+0xbd/0x270 mm/slab.c:3814
 rfcomm_dlc_free+0x19/0x20 net/bluetooth/rfcomm/core.c:328
 rfcomm_dlc_put include/net/bluetooth/rfcomm.h:258 [inline]
 __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:417 [inline]
 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
 rfcomm_dev_ioctl+0x1488/0x18f0 net/bluetooth/rfcomm/tty.c:588
 rfcomm_sock_ioctl+0x71/0xa0 net/bluetooth/rfcomm/sock.c:902
 sock_do_ioctl+0x62/0xa0 net/socket.c:974
 sock_ioctl+0x251/0x430 net/socket.c:1071
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x74/0x80 fs/ioctl.c:692
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45af49
RSP: 002b:00007fbc7b824c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 0000000020000100 RSI: 00000000400452c8 RDI: 0000000000000005
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbc7b8256d4
R13: 00000000004c3c64 R14: 00000000004da258 R15: 00000000ffffffff

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