TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
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: 16267 Comm: syz-executor5 Not tainted 4.4.145-g2241aa9 #78
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c99f6000 task.stack: ffff8800a4650000
RIP: 0010:[<ffffffff8324d6b5>]  [<ffffffff8324d6b5>] tcp_sendmsg+0x455/0x2b10 net/ipv4/tcp.c:1165
RSP: 0018:ffff8800a4657918  EFLAGS: 00010206
RAX: 0000000000000011 RBX: 000000007fb29588 RCX: ffffc900062af000
RDX: 0000000000000001 RSI: ffffffff8324d695 RDI: 0000000000000089
RBP: ffff8800a4657ae8 R08: ffff8801c99f6928 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8801c99f6000 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8800a7099680
FS:  00007f7749156700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f23e2e5bdb8 CR3: 00000000b17b7000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 2031acdcb593e96e ffff8800a4657e88 ffff8800a70996a8 ffff8801c99f6800
 ffff8801c99f7250 fffffbfff0943760 ffff8801baa20000 0000000000000001
 ffff8800b27db4c8 ffff8800a70998d8 ffff8800b27db47c ffff8800a7099e9b
Call Trace:
 [<ffffffff833064b3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f22e1c>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82f22e1c>] sock_sendmsg+0xcc/0x110 net/socket.c:635
 [<ffffffff82f248e5>] ___sys_sendmsg+0x745/0x880 net/socket.c:1962
 [<ffffffff82f26986>] __sys_sendmsg+0xd6/0x190 net/socket.c:1996
 [<ffffffff82f26a6d>] SYSC_sendmsg net/socket.c:2007 [inline]
 [<ffffffff82f26a6d>] SyS_sendmsg+0x2d/0x50 net/socket.c:2003
 [<ffffffff838c84e5>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: 0f 84 13 07 00 00 e8 db 60 10 fe 8b 85 18 ff ff ff 49 8d bd 89 00 00 00 48 89 fa 83 e2 07 89 85 e8 fe ff ff 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 38 d0 7f 08 84 c0 0f 85 86 20 00 00 41 f6 85 89 
RIP  [<ffffffff8324d6b5>] tcp_sendmsg+0x455/0x2b10 net/ipv4/tcp.c:1165
 RSP <ffff8800a4657918>
---[ end trace 6b67bf51d9baacdf ]---