TCP: request_sock_TCPv6: Possible SYN flooding on port 20000. Dropping request.  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
Modules linked in:
CPU: 0 PID: 4458 Comm: syz-executor.4 Not tainted 4.4.174+ #17
task: ffff8801bec05f00 task.stack: ffff8801be958000
RIP: 0010:[<ffffffff822eee2b>]  [<ffffffff822eee2b>] netlink_getsockbyportid net/netlink/af_netlink.c:1112 [inline]
RIP: 0010:[<ffffffff822eee2b>]  [<ffffffff822eee2b>] netlink_unicast+0x1cb/0x700 net/netlink/af_netlink.c:1297
RSP: 0018:ffff8801be95f738  EFLAGS: 00010216
RAX: dffffc0000000048 RBX: 0000000000000000 RCX: ffffc90005567000
RDX: 00000000000008cd RSI: ffffffff822eee24 RDI: ffff8800b40e1c18
RBP: ffff8801be95f7f0 R08: 1ffff10016cc08f2 R09: ffffed0016cc08f7
R10: ffffed0016cc08f6 R11: ffff8800b66047b7 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8800b40e1b40 R15: 0000000000000109
FS:  0000000000000000(0000) GS:ffff8801db600000(0063) knlGS:00000000f5501b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000fad470 CR3: 00000001d5c2c000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8800b6604840 0000000000000030 0000000000000240 1ffff10037d2beed
 dffffc0000000006 dffffc0000000048 0000000041b58ab3 ffffffff82c9f14a
 ffffffff822eec60 ffffffff821f812c 0000000000000000 ffff8800b6604780
Call Trace:
 [<ffffffff822f0386>] netlink_ack+0x236/0x4c0 net/netlink/af_netlink.c:2334
 [<ffffffff822ff60d>] nfnetlink_rcv_batch net/netfilter/nfnetlink.c:319 [inline]
 [<ffffffff822ff60d>] nfnetlink_rcv+0xbdd/0x12b0 net/netfilter/nfnetlink.c:477
 [<ffffffff822ef137>] netlink_unicast_kernel net/netlink/af_netlink.c:1277 [inline]
 [<ffffffff822ef137>] netlink_unicast+0x4d7/0x700 net/netlink/af_netlink.c:1303
 [<ffffffff822efb86>] netlink_sendmsg+0x6b6/0xc80 net/netlink/af_netlink.c:1859
 [<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
 [<ffffffff821da269>] ___sys_sendmsg+0x769/0x890 net/socket.c:1975
 [<ffffffff821dd0c5>] __sys_sendmsg+0xc5/0x160 net/socket.c:2009
 [<ffffffff822acdda>] C_SYSC_sendmsg net/compat.c:725 [inline]
 [<ffffffff822acdda>] compat_SyS_sendmsg+0x2a/0x40 net/compat.c:723
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a
Code: ec a7 01 ff 48 8d 55 98 48 89 d9 4c 89 f6 4c 89 e7 e8 fa f6 ff ff 83 f8 01 0f 85 e6 03 00 00 e8 cc a7 01 ff 48 8b 85 70 ff ff ff <0f> b6 00 84 c0 74 08 3c 03 0f 8e 16 04 00 00 48 8b 85 68 ff ff 
RIP  [<ffffffff822eee2b>] netlink_getsockbyportid net/netlink/af_netlink.c:1112 [inline]
RIP  [<ffffffff822eee2b>] netlink_unicast+0x1cb/0x700 net/netlink/af_netlink.c:1297
 RSP <ffff8801be95f738>
---[ end trace 842dc7cfd0ea4b82 ]---