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BUG: KASAN: stack-out-of-bounds in memcmp+0x126/0x160 lib/string.c:768
Read of size 1 at addr ffff8801ce7a7950 by task syz-executor0/17536

CPU: 1 PID: 17536 Comm: syz-executor0 Not tainted 4.9.135+ #59
 ffff8801ce7a7228 ffffffff81b36bf9 ffffea000739e9c0 ffff8801ce7a7950
 0000000000000000 ffff8801ce7a7950 ffff8801ce7a7938 ffff8801ce7a7260
 ffffffff815009ad ffff8801ce7a7950 0000000000000001 0000000000000000
Call Trace:
 [<ffffffff81b36bf9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b36bf9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff815009ad>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81500db7>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81500db7>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff814f2f64>] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 [<ffffffff81b536f6>] memcmp+0x126/0x160 lib/string.c:768
 [<ffffffff8262cb80>] addr_match include/net/xfrm.h:833 [inline]
 [<ffffffff8262cb80>] __xfrm6_selector_match net/xfrm/xfrm_policy.c:87 [inline]
 [<ffffffff8262cb80>] xfrm_selector_match+0x6a0/0xe40 net/xfrm/xfrm_policy.c:101
 [<ffffffff8262d463>] xfrm_sk_policy_lookup+0x143/0x3c0 net/xfrm/xfrm_policy.c:1268
 [<ffffffff8262d89d>] xfrm_lookup+0x1bd/0xb70 net/xfrm/xfrm_policy.c:2220
 [<ffffffff8262f0e9>] xfrm_lookup_route+0x39/0x140 net/xfrm/xfrm_policy.c:2354
 [<ffffffff826800db>] ip6_dst_lookup_flow+0x17b/0x210 net/ipv6/ip6_output.c:1096
 [<ffffffff826fcb3c>] rawv6_sendmsg+0x8fc/0x2a70 net/ipv6/raw.c:911
 [<ffffffff82582e63>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770
 [<ffffffff8228e13b>] sock_sendmsg_nosec net/socket.c:648 [inline]
 [<ffffffff8228e13b>] sock_sendmsg+0xbb/0x110 net/socket.c:658
 [<ffffffff8228fb9a>] ___sys_sendmsg+0x47a/0x840 net/socket.c:1982
 [<ffffffff822930a1>] __sys_sendmmsg+0x161/0x3d0 net/socket.c:2072
 [<ffffffff82293345>] SYSC_sendmmsg net/socket.c:2103 [inline]
 [<ffffffff82293345>] SyS_sendmmsg+0x35/0x60 net/socket.c:2098
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82803413>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea000739e9c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ce7a7800: f2 f2 f2 f2 00 00 00 00 00 00 00 00 f2 f2 f2 f2
 ffff8801ce7a7880: 00 00 f2 f2 f2 f2 f2 f2 00 00 f2 f2 f2 f2 f2 f2
>ffff8801ce7a7900: 00 00 00 00 00 00 00 00 00 00 f2 f2 00 00 00 00
                                                 ^
 ffff8801ce7a7980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801ce7a7a00: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
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