bisecting fixing commit since 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796
building syzkaller on 5d7b90f1af2e3bf33992b75e7fcf0bab6bf49bd6
testing commit 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796 with gcc (GCC) 8.1.0
kernel signature: 8e3b9e458557a8b4e51b255b84684e857b65d157e5839128fab536fcc86e16d3
all runs: crashed: WARNING: ODEBUG bug in rfcomm_dlc_free
testing current HEAD 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14
testing commit 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14 with gcc (GCC) 8.1.0
kernel signature: 6cfa6c5639e00f8dd0d30b81180e5baf22c0ff9e9ea8184da02a8d4e970a7e6a
all runs: crashed: WARNING: ODEBUG bug in rfcomm_dlc_free
revisions tested: 2, total time: 25m46.833583336s (build: 17m37.451816612s, test: 7m10.109417184s)
the crash still happens on HEAD
commit msg: Linux 4.14.173
crash: WARNING: ODEBUG bug in rfcomm_dlc_free
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: 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
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
------------[ cut here ]------------
WARNING: CPU: 1 PID: 7335 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: 1 PID: 7335 Comm: syz-executor.1 Not tainted 4.14.173-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
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
 panic+0x1b0/0x358 kernel/panic.c:183
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
 __warn.cold.8+0x25/0x2c kernel/panic.c:547
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
 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
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
 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:ffff88807d7afa70 EFLAGS: 00010082
batman_adv: batadv0: Interface activated: batadv_slave_1
RAX: 000000000000005e RBX: 0000000000000003 RCX: 0000000000000000
RDX: 000000000000005e RSI: ffffffff86cbf2a0 RDI: ffffed100faf5f45
RBP: ffff88807d7afa98 R08: 0000000000000000 R09: 0000000000000000
R10: fffffbfff1341cd1 R11: ffff88809870e600 R12: ffffffff86cba4e0
R13: ffffffff85d17af0 R14: 0000000000000000 R15: ffff8880a97367e8
 __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: 0033:0x45c6c9
RSP: 002b:00007fb94f005c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb94f0066d4 RCX: 000000000045c6c9
RDX: 0000000020000100 RSI: 00000000400452c8 RDI: 0000000000000006
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000312 R14: 00000000004c5631 R15: 000000000076bf2c

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