syzbot

keychord: using input dev AT Translated Set 2 keyboard for fevent
keychord: using input dev AT Translated Set 2 keyboard for fevent
keychord: using input dev AT Translated Set 2 keyboard for fevent
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3358 at lib/list_debug.c:36 __list_add+0x169/0x1c0 lib/list_debug.c:34
list_add double add: new=ffff8801c6314968, prev=ffff8801c6314968, next=ffffffff84876140.
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 3358 Comm: syzkaller268134 Not tainted 4.9.39-ga1e4c795 #8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801c95d79f8 ffffffff81eacd59 ffffffff83a48d40 ffff8801c95d7ad0
 ffffffff83c3a600 ffffffff81f13829 0000000000000009 ffff8801c95d7ac0
 ffffffff814265a6 0000000041b58ab3 ffffffff84169b8d ffffffff814263f2
Call Trace:
 [<ffffffff81eacd59>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eacd59>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff814265a6>] panic+0x1b4/0x3a0 kernel/panic.c:179
 [<ffffffff81133b94>] __warn+0x1c4/0x1e0 kernel/panic.c:542
 [<ffffffff81133c5e>] warn_slowpath_fmt+0xae/0xe0 kernel/panic.c:565
 [<ffffffff81f13829>] __list_add+0x169/0x1c0 lib/list_debug.c:34
 [<ffffffff82afa640>] list_add_tail include/linux/list.h:77 [inline]
 [<ffffffff82afa640>] input_register_handler+0xa0/0x150 drivers/input/input.c:2222
 [<ffffffff82b49545>] keychord_write+0x575/0x810 drivers/input/misc/keychord.c:317
 [<ffffffff81572d6b>] __vfs_write+0xfb/0x660 fs/read_write.c:510
 [<ffffffff81576df0>] vfs_write+0x170/0x4e0 fs/read_write.c:560
 [<ffffffff8157a724>] SYSC_write fs/read_write.c:607 [inline]
 [<ffffffff8157a724>] SyS_write+0xd4/0x1a0 fs/read_write.c:599
 [<ffffffff83965985>] entry_SYSCALL_64_fastpath+0x23/0xc6
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..