TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
==================================================================
BUG: KASAN: stack-out-of-bounds in memcmp+0x126/0x160 lib/string.c:742
Read of size 1 at addr ffff8801c83af8e0 by task syz-executor6/20244

CPU: 0 PID: 20244 Comm: syz-executor6 Not tainted 4.4.138-gcf21a9a #64
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 ad3ac60818674d2f ffff8801c83af410 ffffffff81e0ed0d
 ffffea000720ebc0 ffff8801c83af8e0 0000000000000000 ffff8801c83af8e0
 0000000000000000 ffff8801c83af448 ffffffff81515a16 ffff8801c83af8e0
Call Trace:
 [<ffffffff81e0ed0d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0ed0d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81515a16>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff81515d35>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81515d35>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f97c4>] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:426
 [<ffffffff81e2b196>] memcmp+0x126/0x160 lib/string.c:742
 [<ffffffff833ce91d>] addr_match include/net/xfrm.h:837 [inline]
 [<ffffffff833ce91d>] __xfrm6_selector_match net/xfrm/xfrm_policy.c:81 [inline]
 [<ffffffff833ce91d>] xfrm_selector_match+0x12d/0xe50 net/xfrm/xfrm_policy.c:95
 [<ffffffff833cf791>] xfrm_sk_policy_lookup+0x151/0x350 net/xfrm/xfrm_policy.c:1236
 [<ffffffff833d2525>] xfrm_lookup+0x1b5/0xb70 net/xfrm/xfrm_policy.c:2184
 [<ffffffff833d3df9>] xfrm_lookup_route+0x39/0x1b0 net/xfrm/xfrm_policy.c:2318
 [<ffffffff83428c47>] ip6_dst_lookup_flow+0x1b7/0x2f0 net/ipv6/ip6_output.c:1072
 [<ffffffff834cd6c8>] tcp_v6_connect+0xd58/0x1b70 net/ipv6/tcp_ipv6.c:249
 [<ffffffff832f9b89>] __inet_stream_connect+0x2a9/0xc30 net/ipv4/af_inet.c:615
 [<ffffffff83249910>] tcp_sendmsg_fastopen net/ipv4/tcp.c:1092 [inline]
 [<ffffffff83249910>] tcp_sendmsg+0x1600/0x2b00 net/ipv4/tcp.c:1112
 [<ffffffff83300dd3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f1e22c>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82f1e22c>] sock_sendmsg+0xcc/0x110 net/socket.c:635
 [<ffffffff82f1ef0c>] SYSC_sendto+0x21c/0x370 net/socket.c:1665
 [<ffffffff82f21590>] SyS_sendto+0x40/0x50 net/socket.c:1633
 [<ffffffff838c2725>] entry_SYSCALL_64_fastpath+0x22/0x9e

The buggy address belongs to the page:
page:ffffea000720ebc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c83af780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c83af800: 00 00 00 00 00 00 f1 f1 f1 f1 00 00 f2 f2 f2 f2
>ffff8801c83af880: f2 f2 00 00 00 00 00 00 00 00 00 00 f2 f2 00 00
                                                       ^
 ffff8801c83af900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c83af980: 00 00 00 f1 f1 f1 f1 00 00 00 00 00 f2 f2 f2 00
==================================================================