TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
l2tp_core: tunl 3: sockfd_lookup(fd=7) returned -9
BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
IP: [<ffffffff836c3e40>] sock_hold include/net/sock.h:584 [inline]
IP: [<ffffffff836c3e40>] l2tp_session_create+0xc60/0x16f0 net/l2tp/l2tp_core.c:1911
PGD 1d409f067 [  297.985694] PUD 1ccd21067 
Oops: 0002 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 26617 Comm: syz-executor5 Not tainted 4.9.119-g9dc978d #75
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff880192149800 task.stack: ffff8801cee88000
RIP: 0010:[<ffffffff836c3e40>]  [<ffffffff836c3e40>] sock_hold include/net/sock.h:584 [inline]
RIP: 0010:[<ffffffff836c3e40>]  [<ffffffff836c3e40>] l2tp_session_create+0xc60/0x16f0 net/l2tp/l2tp_core.c:1911
RSP: 0018:ffff8801cee8fac0  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801d966ea00 RCX: 1ffff1003242941d
RDX: 1ffff1003afa7d70 RSI: ffff88019214a0c8 RDI: ffff8801d7d3eb80
RBP: ffff8801cee8fb60 R08: ffff88019214a0e8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d7d3ea58
R13: 0000000000000000 R14: ffff8801d7d3ea00 R15: 0000000000000000
FS:  00007f505b12d700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 000000015274a000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff836c40b7 ffffffff836c5151 ffff8801a4fd9948 0000000000000000
 ffff8801d7d3ea00 ffff8801d966eb58 ffff8801d7d3ea58 ffff8801d966eb50
 ffff8801d966eab0 ffff8801d7d3ea20 ffff8801a4fd9100 0000000000000000
Call Trace:
 [<ffffffff836c8ff7>] pppol2tp_connect+0x10d7/0x18f0 net/l2tp/l2tp_ppp.c:718
 [<ffffffff83019958>] SYSC_connect+0x1b8/0x300 net/socket.c:1563
 [<ffffffff8301c224>] SyS_connect+0x24/0x30 net/socket.c:1544
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 00 00 49 8d be 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 7b 09 00 00 49 8b 86 80 01 00 00 <f0> ff 80 80 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 55 d0 
RIP  [<ffffffff836c3e40>] sock_hold include/net/sock.h:584 [inline]
RIP  [<ffffffff836c3e40>] l2tp_session_create+0xc60/0x16f0 net/l2tp/l2tp_core.c:1911
 RSP <ffff8801cee8fac0>
CR2: 0000000000000080
---[ end trace 5cdce293d25ac95c ]---
BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
IP: [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 net/l2tp/l2tp_core.c:1765
PGD 1d409f067 
PUD 1ccd21067 
PMD 0 

Oops: 0002 [#2] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 26610 Comm: syz-executor5 Tainted: G      D         4.9.119-g9dc978d #75
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d963e000 task.stack: ffff8801a3820000
RIP: 0010:[<ffffffff836bf9cc>]  [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 net/l2tp/l2tp_core.c:1765
RSP: 0018:ffff8801a3827be8  EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8801d966ea00 RCX: ffffc9000131f000
RDX: 1ffff1003afa7d70 RSI: ffffffff836bf9a1 RDI: ffff8801d7d3eb80
RBP: ffff8801a3827c08 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d7d3ea00
R13: ffff8801d966ea08 R14: 0000000000000000 R15: ffff8801d7d3ea58
FS:  00007f505b14e700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 000000015274a000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d966eaa8 dffffc0000000000 ffff8801d966ea00 0000000000000000
 ffff8801a3827c60 ffffffff836c0254 ffff8801d7d3ead8 ffffed003afa7d4b
 ffff8801d7d3ea58 ffff8801d7d3ea20 ffff8801d7d3ea00 ffff8801d478ed40
Call Trace:
 [<ffffffff836c0254>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:297 [inline]
 [<ffffffff836c0254>] l2tp_tunnel_closeall+0x284/0x350 net/l2tp/l2tp_core.c:1373
 [<ffffffff836c0a82>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff830230f5>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff8302ab83>] sk_destruct+0x63/0x80 net/core/sock.c:1463
 [<ffffffff8302abef>] __sk_free+0x4f/0x220 net/core/sock.c:1471
 [<ffffffff8302adeb>] sk_free+0x2b/0x40 net/core/sock.c:1482
 [<ffffffff8302caea>] sock_put include/net/sock.h:1588 [inline]
 [<ffffffff8302caea>] sk_common_release+0x1fa/0x300 net/core/sock.c:2757
 [<ffffffff833f5575>] udp_lib_close+0x15/0x20 include/net/udp.h:203
 [<ffffffff834240af>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:434
 [<ffffffff83015ab6>] sock_release+0x96/0x1c0 net/socket.c:600
 [<ffffffff83015bf6>] sock_close+0x16/0x20 net/socket.c:1047
 [<ffffffff81578693>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff81578bb5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8119838c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8100559c>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 49 8d bc 24 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 c6 00 00 00 4d 8b b4 24 80 01 00 00 <f0> 41 ff 8e 80 00 00 00 74 69 e8 f5 f0 c9 fd 4c 89 ea 48 b8 00 
RIP  [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 net/l2tp/l2tp_core.c:1765
 RSP <ffff8801a3827be8>
CR2: 0000000000000080
---[ end trace 5cdce293d25ac95d ]---