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BUG: KASAN: stack-out-of-bounds in memcmp+0x126/0x160 lib/string.c:768
Read of size 1 at addr ffff8801b8927840 by task syzkaller056349/3757

CPU: 0 PID: 3757 Comm: syzkaller056349 Not tainted 4.9.93-geba1ffe #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801b8927300 ffffffff81d9c2b9 ffffea0006e249c0 ffff8801b8927840
 0000000000000000 ffff8801b8927840 ffff8801b8927828 ffff8801b8927338
 ffffffff8156536b ffff8801b8927840 0000000000000001 0000000000000000
Call Trace:
 [<ffffffff81d9c2b9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9c2b9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8156536b>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff815655df>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff815655df>] kasan_report.cold.6+0xac/0x2f5 mm/kasan/report.c:412
 [<ffffffff81539394>] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 [<ffffffff81dba206>] memcmp+0x126/0x160 lib/string.c:768
 [<ffffffff833d86a2>] addr_match include/net/xfrm.h:833 [inline]
 [<ffffffff833d86a2>] __xfrm6_selector_match net/xfrm/xfrm_policy.c:87 [inline]
 [<ffffffff833d86a2>] xfrm_selector_match+0x122/0xe10 net/xfrm/xfrm_policy.c:101
 [<ffffffff833d94d3>] xfrm_sk_policy_lookup+0x143/0x3c0 net/xfrm/xfrm_policy.c:1268
 [<ffffffff833dbaf5>] xfrm_lookup+0x1b5/0xb70 net/xfrm/xfrm_policy.c:2217
 [<ffffffff833dd3b9>] xfrm_lookup_route+0x39/0x1b0 net/xfrm/xfrm_policy.c:2351
 [<ffffffff83432b2b>] ip6_dst_lookup_flow+0x17b/0x210 net/ipv6/ip6_output.c:1092
 [<ffffffff834d608e>] tcp_v6_connect+0xd8e/0x1b40 net/ipv6/tcp_ipv6.c:248
 [<ffffffff832fe960>] __inet_stream_connect+0x6e0/0xbf0 net/ipv4/af_inet.c:627
 [<ffffffff8324a204>] tcp_sendmsg_fastopen net/ipv4/tcp.c:1116 [inline]
 [<ffffffff8324a204>] tcp_sendmsg+0x1d94/0x2ff0 net/ipv4/tcp.c:1144
 [<ffffffff83305ea3>] 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
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff838d5953>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea0006e249c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801b8927700: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2
 ffff8801b8927780: f2 f2 f2 f2 f2 f2 00 00 f2 f2 f2 f2 f2 f2 00 00
>ffff8801b8927800: 00 00 00 00 00 00 00 00 f2 f2 00 00 00 00 00 00
                                           ^
 ffff8801b8927880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1
 ffff8801b8927900: f1 f1 f1 00 00 00 00 00 f2 f2 f2 00 00 00 00 00
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