syzbot

netlink: 8 bytes leftover after parsing attributes in process `syz-executor3'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor3'.
nf_conntrack: default automatic helper assignment has been turned off for security reasons and CT-based  firewall rule not found. Use the iptables CT target to attach helpers instead.
INFO: task syz-executor4:11697 blocked for more than 140 seconds.
      Not tainted 4.18.0-rc4-next-20180713+ #7
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D24152 11697   4474 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2848 [inline]
 __schedule+0x87c/0x1ed0 kernel/sched/core.c:3496
 schedule+0xfb/0x450 kernel/sched/core.c:3540
 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3598
 __mutex_lock_common kernel/locking/mutex.c:1003 [inline]
 __mutex_lock+0xbf5/0x1680 kernel/locking/mutex.c:1073
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
 tty_lock+0x70/0xa0 drivers/tty/tty_mutex.c:19
 tty_release+0x196/0x1300 drivers/tty/tty_io.c:1638
 __fput+0x35d/0x930 fs/file_table.c:252
 ____fput+0x15/0x20 fs/file_table.c:288
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x40fb91
Code: Bad RIP value.
RSP: 002b:00007ffe24d6f3d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000015 RCX: 000000000040fb91
RDX: 0000000000000000 RSI: 00000000007309b8 RDI: 0000000000000014
RBP: 0000000000000013 R08: 00007ffe24d6f350 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ffe24d6fa80 R15: 00000000007034c0
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 901 Comm: khungtaskd Not tainted 4.18.0-rc4-next-20180713+ #7
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+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.3+0x48/0x88 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:144 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:231 [inline]
 watchdog+0xb81/0x10f0 kernel/hung_task.c:292
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 11700 Comm: syz-executor4 Not tainted 4.18.0-rc4-next-20180713+ #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:enqueue_pushable_task+0xbb/0x490 kernel/sched/rt.c:374
Code: ff ff ff 48 89 d7 48 89 ce 48 89 8d 28 ff ff ff 48 89 95 30 ff ff ff e8 a3 05 3d 06 4c 89 ee 4c 8d 45 d8 48 8b 95 30 ff ff ff <48> c1 ee 03 48 8b 8d 28 ff ff ff 48 8b 85 20 ff ff ff 42 0f b6 3c 
RSP: 0018:ffff88019a597290 EFLAGS: 00000082
RAX: 0000000000000000 RBX: ffff8801c1c94180 RCX: 0000000000000000
RDX: ffff8801c1c94520 RSI: ffff8801c1c941e4 RDI: ffffed00334b2e40
RBP: ffff88019a597370 R08: ffff88019a597348 R09: ffffed003b5e5a5c
R10: ffffed003b5e5a5c R11: ffff8801daf2d2e3 R12: 1ffff100334b2e55
R13: ffff8801c1c941e4 R14: dffffc0000000000 R15: ffffffff87ea8f20
FS:  00007f094e8e1700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32d22000 CR3: 00000001ae553000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 put_prev_task_rt+0x81/0xa0 kernel/sched/rt.c:1591
 put_prev_task kernel/sched/sched.h:1542 [inline]
 pick_next_task_rt+0x183/0x820 kernel/sched/rt.c:1570
 pick_next_task kernel/sched/core.c:3355 [inline]
 __schedule+0x1401/0x1ed0 kernel/sched/core.c:3470
 schedule+0xfb/0x450 kernel/sched/core.c:3540
 do_sched_yield+0x18f/0x250 kernel/sched/core.c:4973
 yield+0xa5/0xe0 kernel/sched/core.c:5048
 tasklet_kill+0x4e/0xd0 kernel/softirq.c:562
 ppp_sync_close+0x96/0x110 drivers/net/ppp/ppp_synctty.c:238
 ppp_sync_hangup+0x15/0x20 drivers/net/ppp/ppp_synctty.c:254
 tty_ldisc_hangup+0x138/0x640 drivers/tty/tty_ldisc.c:717
 __tty_hangup.part.21+0x2da/0x6e0 drivers/tty/tty_io.c:621
 __tty_hangup drivers/tty/tty_io.c:571 [inline]
 tty_vhangup+0x21/0x30 drivers/tty/tty_io.c:694
 pty_close+0x3bd/0x510 drivers/tty/pty.c:78
 tty_release+0x4b3/0x1300 drivers/tty/tty_io.c:1656
 __fput+0x35d/0x930 fs/file_table.c:252
 ____fput+0x15/0x20 fs/file_table.c:288
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455ab9
Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007f094e8e0c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f094e8e16d4 RCX: 0000000000455ab9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004eb612 R14: 00000000004c8d40 R15: 0000000000000000