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BUG: KASAN: stack-out-of-bounds in memcmp+0x126/0x160 lib/string.c:768
Read of size 1 at addr ffff8801cd4bf830 by task syz-executor1/10331

CPU: 0 PID: 10331 Comm: syz-executor1 Not tainted 4.9.92-g7cd9561 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801cd4bf2f0 ffffffff81d9c489 ffffea0007352fc0 ffff8801cd4bf830
 0000000000000000 ffff8801cd4bf830 ffff8801cd4bf818 ffff8801cd4bf328
 ffffffff8156556b ffff8801cd4bf830 0000000000000001 0000000000000000
Call Trace:
 [<ffffffff81d9c489>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9c489>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8156556b>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff815657df>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff815657df>] kasan_report.cold.6+0xac/0x2f5 mm/kasan/report.c:412
 [<ffffffff81539594>] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 [<ffffffff81dba3d6>] memcmp+0x126/0x160 lib/string.c:768
 [<ffffffff833d8692>] addr_match include/net/xfrm.h:833 [inline]
 [<ffffffff833d8692>] __xfrm6_selector_match net/xfrm/xfrm_policy.c:87 [inline]
 [<ffffffff833d8692>] xfrm_selector_match+0x122/0xe10 net/xfrm/xfrm_policy.c:101
 [<ffffffff833d94c3>] xfrm_sk_policy_lookup+0x143/0x3c0 net/xfrm/xfrm_policy.c:1268
 [<ffffffff833dbae5>] xfrm_lookup+0x1b5/0xb70 net/xfrm/xfrm_policy.c:2217
 [<ffffffff833dd3a9>] xfrm_lookup_route+0x39/0x1b0 net/xfrm/xfrm_policy.c:2351
 [<ffffffff83432a7b>] ip6_dst_lookup_flow+0x17b/0x210 net/ipv6/ip6_output.c:1092
 [<ffffffff834d5fde>] tcp_v6_connect+0xd8e/0x1b40 net/ipv6/tcp_ipv6.c:248
 [<ffffffff832fe940>] __inet_stream_connect+0x6e0/0xbf0 net/ipv4/af_inet.c:627
 [<ffffffff8324a1e4>] tcp_sendmsg_fastopen net/ipv4/tcp.c:1116 [inline]
 [<ffffffff8324a1e4>] tcp_sendmsg+0x1d94/0x2ff0 net/ipv4/tcp.c:1144
 [<ffffffff83305e83>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770
 [<ffffffff82ef3fcc>] sock_sendmsg_nosec net/socket.c:635 [inline]
 [<ffffffff82ef3fcc>] sock_sendmsg+0xcc/0x110 net/socket.c:645
 [<ffffffff82ef4cbc>] SYSC_sendto+0x21c/0x370 net/socket.c:1670
 [<ffffffff82ef72d0>] SyS_sendto+0x40/0x50 net/socket.c:1638
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff838d6fd0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

The buggy address belongs to the page:
page:ffffea0007352fc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cd4bf700: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2 f2 f2
 ffff8801cd4bf780: f2 f2 f2 f2 00 00 f2 f2 f2 f2 f2 f2 00 00 00 00
>ffff8801cd4bf800: 00 00 00 00 00 00 f2 f2 00 00 00 00 00 00 00 00
                                     ^
 ffff8801cd4bf880: 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1
 ffff8801cd4bf900: f1 00 00 00 00 00 f2 f2 f2 00 00 00 00 00 00 00
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