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BUG: KASAN: stack-out-of-bounds in xfrm_state_find+0x303d/0x3170 net/xfrm/xfrm_state.c:1051
Read of size 4 at addr ffff8801c8d87520 by task syz-executor6/17631

CPU: 1 PID: 17631 Comm: syz-executor6 Not tainted 4.13.0-rc6+ #34
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x24e/0x340 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 xfrm_state_find+0x303d/0x3170 net/xfrm/xfrm_state.c:1051
 xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:1388 [inline]
 xfrm_tmpl_resolve+0x309/0xc00 net/xfrm/xfrm_policy.c:1432
 xfrm_resolve_and_create_bundle+0x186/0x24a0 net/xfrm/xfrm_policy.c:1830
 xfrm_lookup+0xef8/0x2520 net/xfrm/xfrm_policy.c:2141
 xfrm_lookup_route+0x39/0x1a0 net/xfrm/xfrm_policy.c:2260
 ip_route_output_flow+0x7c/0xa0 net/ipv4/route.c:2549
 udp_sendmsg+0x1958/0x2c70 net/ipv4/udp.c:1022
 udpv6_sendmsg+0x735/0x31b0 net/ipv6/udp.c:1177
 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:633 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:643
 ___sys_sendmsg+0x31c/0x890 net/socket.c:2049
 __sys_sendmmsg+0x1e6/0x5f0 net/socket.c:2139
 SYSC_sendmmsg net/socket.c:2170 [inline]
 SyS_sendmmsg+0x35/0x60 net/socket.c:2165
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x451e59
RSP: 002b:00007f280dd1ac08 EFLAGS: 00000216 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 0000000000451e59
RDX: 0000000000000002 RSI: 0000000020f38000 RDI: 0000000000000005
RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000800 R11: 0000000000000216 R12: 00000000004bb51e
R13: 00000000ffffffff R14: 000000000000000a R15: 0000000000000001

The buggy address belongs to the page:
page:ffffea00072361c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x200000000000000()
raw: 0200000000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c8d87400: 00 f1 f1 f1 f1 00 f2 f2 f2 f2 f2 f2 f2 f8 f2 f2
 ffff8801c8d87480: f2 f2 f2 f2 f2 00 00 00 00 f2 f2 f2 f2 00 00 00
>ffff8801c8d87500: 00 00 00 00 f2 f2 f2 f2 f2 00 00 00 00 00 00 00
                               ^
 ffff8801c8d87580: 00 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00 00 00
 ffff8801c8d87600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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