hrtimer: interrupt took 29112 ns
l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9
BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
IP: [<ffffffff835aab88>] sock_hold include/net/sock.h:589 [inline]
IP: [<ffffffff835aab88>] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809
PGD bb85c067 PUD b95ec067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 4400 Comm: syz-executor0 Not tainted 4.4.153-g5e24b4e #26
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800b7afb000 task.stack: ffff8800aef30000
RIP: 0010:[<ffffffff835aab88>]  [<ffffffff835aab88>] sock_hold include/net/sock.h:589 [inline]
RIP: 0010:[<ffffffff835aab88>]  [<ffffffff835aab88>] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809
RSP: 0018:ffff8800aef37ad0  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801d491ea00 RCX: 0000000000000006
RDX: 1ffff1003a923d70 RSI: ffffffff835a4c93 RDI: ffff8801d491eb80
RBP: ffff8800aef37b40 R08: 000000000000000a R09: 000000000000ffff
R10: ffffed003a95b248 R11: ffffffff8463a200 R12: ffff8801d4ad9228
R13: ffff8800aef37c58 R14: ffff8801d4ad9180 R15: ffffffff835a38c0
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f7723b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000080 CR3: 00000000b8e4d000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81140aba ffff8801d491ea20 ffff8801d4ad92d8 ffff8801d4ad9190
 ffffffff838cc1e0 ffff8801d4ad9230 ffff8801d4ad92d0 ffff8801d491eae0
 ffffffff00000000 ffff8800aef88000 0000000000000000 ffff8800aef88030
Call Trace:
 [<ffffffff835aef80>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f27ef8>] SYSC_connect+0x1b8/0x300 net/socket.c:1570
 [<ffffffff82f2a844>] SyS_connect+0x24/0x30 net/socket.c:1551
 [<ffffffff81006d94>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d94>] do_fast_syscall_32+0x324/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838ce1c3>] sysenter_flags_fixed+0xd/0x1a
Code: 00 00 48 8d bb 80 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 36 06 00 00 48 8b 83 80 01 00 00 <f0> ff 80 80 00 00 00 48 8d 43 20 48 89 c7 48 89 45 b0 e8 f1 13 
RIP  [<ffffffff835aab88>] sock_hold include/net/sock.h:589 [inline]
RIP  [<ffffffff835aab88>] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809
 RSP <ffff8800aef37ad0>
CR2: 0000000000000080
---[ end trace bd8bd4b30988c2e7 ]---