==================================================================
BUG: KASAN: use-after-free in xfrm_policy_insert_list+0xd7f/0x1020 net/xfrm/xfrm_policy.c:1532
Read of size 1 at addr ffff8881b319ef99 by task syz-executor3/26819

CPU: 0 PID: 26819 Comm: syz-executor3 Not tainted 4.20.0-rc7+ #360
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d3/0x2c6 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 xfrm_policy_insert_list+0xd7f/0x1020 net/xfrm/xfrm_policy.c:1532
 xfrm_policy_inexact_insert+0x166/0xee0 net/xfrm/xfrm_policy.c:1195
 xfrm_policy_insert+0x639/0x850 net/xfrm/xfrm_policy.c:1570
 pfkey_spdadd+0x10f8/0x19d0 net/key/af_key.c:2339
 pfkey_process+0x851/0x9a0 net/key/af_key.c:2844
 pfkey_sendmsg+0x5df/0xfb0 net/key/af_key.c:3683
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
 __sys_sendmsg+0x11d/0x280 net/socket.c:2154
 __do_sys_sendmsg net/socket.c:2163 [inline]
 __se_sys_sendmsg net/socket.c:2161 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457759
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f857dcbcc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457759
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f857dcbd6d4
R13: 00000000004c498a R14: 00000000004d8040 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea0006cc6780 count:0 mapcount:-128 mapping:0000000000000000 index:0xffff8881b319f200
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 ffffea0006437108 ffffea000762b988 0000000000000000
raw: ffff8881b319f200 0000000000000001 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881b319ee80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881b319ef00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881b319ef80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff8881b319f000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881b319f080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================