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BUG: KASAN: stack-out-of-bounds in memcmp+0x126/0x160 lib/string.c:742
Read of size 1 at addr ffff8800a2a6f920 by task syz-executor5/13492

CPU: 1 PID: 13492 Comm: syz-executor5 Not tainted 4.4.159+ #108
 0000000000000000 8a4d7f031e7c53a2 ffff8800a2a6f458 ffffffff81a994bd
 ffffea00028a9bc0 ffff8800a2a6f920 0000000000000000 ffff8800a2a6f920
 ffff8800a2a6f908 ffff8800a2a6f490 ffffffff8148a809 ffff8800a2a6f920
Call Trace:
 [<ffffffff81a994bd>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81a994bd>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8148a809>] print_address_description+0x6c/0x217 mm/kasan/report.c:252
 [<ffffffff8148ab29>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8148ab29>] kasan_report.cold.6+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff8147f744>] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:426
 [<ffffffff81ab5576>] memcmp+0x126/0x160 lib/string.c:742
 [<ffffffff8253d3c0>] addr_match include/net/xfrm.h:837 [inline]
 [<ffffffff8253d3c0>] __xfrm6_selector_match net/xfrm/xfrm_policy.c:81 [inline]
 [<ffffffff8253d3c0>] xfrm_selector_match+0x6a0/0xe50 net/xfrm/xfrm_policy.c:95
 [<ffffffff8253dcc1>] xfrm_sk_policy_lookup+0x151/0x350 net/xfrm/xfrm_policy.c:1241
 [<ffffffff8253e07d>] xfrm_lookup+0x1bd/0xb70 net/xfrm/xfrm_policy.c:2192
 [<ffffffff8253f8d9>] xfrm_lookup_route+0x39/0x140 net/xfrm/xfrm_policy.c:2326
 [<ffffffff8258f867>] ip6_dst_lookup_flow+0x1b7/0x2f0 net/ipv6/ip6_output.c:1072
 [<ffffffff826343be>] tcp_v6_connect+0xcfe/0x1b00 net/ipv6/tcp_ipv6.c:249
 [<ffffffff824952d9>] __inet_stream_connect+0x2a9/0xc30 net/ipv4/af_inet.c:615
 [<ffffffff823e9547>] tcp_sendmsg_fastopen net/ipv4/tcp.c:1092 [inline]
 [<ffffffff823e9547>] tcp_sendmsg+0x1a07/0x2b30 net/ipv4/tcp.c:1112
 [<ffffffff824963c3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821c2ebb>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821c2ebb>] sock_sendmsg+0xbb/0x110 net/socket.c:648
 [<ffffffff821c70e0>] SYSC_sendto net/socket.c:1678 [inline]
 [<ffffffff821c70e0>] SyS_sendto+0x220/0x370 net/socket.c:1646
 [<ffffffff82705ca1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

The buggy address belongs to the page:
page:ffffea00028a9bc0 count:0 mapcount:0 mapping:          (null) index:0x1
flags: 0x0()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8800a2a6f800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
 ffff8800a2a6f880: f1 f1 00 00 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00
>ffff8800a2a6f900: 00 00 00 00 f2 f2 00 00 00 00 00 00 00 00 00 00
                               ^
 ffff8800a2a6f980: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
 ffff8800a2a6fa00: 00 00 00 00 00 f2 f2 f2 00 00 00 00 00 00 00 00
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