l2tp_core: tunl 4: sockfd_lookup(fd=4) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=3) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=3) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=3) returned -9
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 4103 Comm: syz-executor0 Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9299800 task.stack: ffff8801d88d8000
RIP: 0010:[<ffffffff83468b00>]  [<ffffffff83468b00>] __read_once_size include/linux/compiler.h:218 [inline]
RIP: 0010:[<ffffffff83468b00>]  [<ffffffff83468b00>] sk_dst_get include/net/sock.h:1740 [inline]
RIP: 0010:[<ffffffff83468b00>]  [<ffffffff83468b00>] pppol2tp_connect+0x7e0/0x1930 net/l2tp/l2tp_ppp.c:755
RSP: 0018:ffff8801d88dfb50  EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8800ba9f4000 RCX: ffffffff83468ae8
RDX: 000000000000003b RSI: ffffffff839fef20 RDI: 00000000000001d8
RBP: ffff8801d88dfd00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 1ffff1003b11bf36 R12: ffff8800bac7dd80
R13: 0000000000000000 R14: 0000000000001007 R15: 1ffff1003b11bf73
FS:  0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:00000000f7717b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f76f6db0 CR3: 00000001d1284000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff83468a89 00000003d92ba3f0 ffff880100000003 ffff8800ba9f4198
 ffff8800ba9f4900 ffff8800bac7e150 ffff8800bac7dd92 ffff8800bac7ddb0
 ffff8800ba9f4780 0000000041b58ab3 ffffffff84011a60 ffffffff83468320
Call Trace:
 [<ffffffff82df21b6>] SYSC_connect+0x1b6/0x310 net/socket.c:1557
 [<ffffffff82df4a24>] SyS_connect+0x24/0x30 net/socket.c:1538
 [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
 [<ffffffff8377b2aa>] sysenter_flags_fixed+0xd/0x17
Code: fd 80 3d 69 3d 37 01 00 0f 84 ca 08 00 00 e8 98 8b ef fd 49 8d bd d8 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 60 0d 00 00 4d 8b b5 d8 01 00 00 e8 aa d8 e1 
RIP  [<ffffffff83468b00>] __read_once_size include/linux/compiler.h:218 [inline]
RIP  [<ffffffff83468b00>] sk_dst_get include/net/sock.h:1740 [inline]
RIP  [<ffffffff83468b00>] pppol2tp_connect+0x7e0/0x1930 net/l2tp/l2tp_ppp.c:755
 RSP <ffff8801d88dfb50>
---[ end trace 0ad6b29bc3397505 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..