x86/PAT: syz-executor.4:12986 map pfn RAM range req write-combining for [mem 0x1e2800000-0x1e2802fff], got write-back
==================================================================
BUG: KASAN: use-after-free in _decode_session6+0xd2d/0x13d0 net/ipv6/xfrm6_policy.c:136
Read of size 1 at addr ffff88809fbe7812 by task syz-executor.5/12991

CPU: 1 PID: 12991 Comm: syz-executor.5 Not tainted 4.14.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
x86/PAT: syz-executor.4:12994 map pfn RAM range req write-combining for [mem 0x1e0700000-0x1e0702fff], got write-back
 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393
 _decode_session6+0xd2d/0x13d0 net/ipv6/xfrm6_policy.c:136
 __xfrm_decode_session+0x5a/0x110 net/xfrm/xfrm_policy.c:2247
 xfrm_decode_session include/net/xfrm.h:1174 [inline]
 vti_tunnel_xmit+0x135/0x16c0 net/ipv4/ip_vti.c:327
 __netdev_start_xmit include/linux/netdevice.h:4039 [inline]
 netdev_start_xmit include/linux/netdevice.h:4048 [inline]
 xmit_one net/core/dev.c:3009 [inline]
 dev_hard_start_xmit+0x186/0x890 net/core/dev.c:3025
 sch_direct_xmit+0x25f/0x510 net/sched/sch_generic.c:186
 qdisc_restart net/sched/sch_generic.c:249 [inline]
 __qdisc_run+0x1b6/0xde0 net/sched/sch_generic.c:257
 __dev_xmit_skb net/core/dev.c:3235 [inline]
 __dev_queue_xmit+0x1573/0x25c0 net/core/dev.c:3493
 neigh_output include/net/neighbour.h:500 [inline]
 ip6_finish_output2+0x992/0x2150 net/ipv6/ip6_output.c:120
 ip6_finish_output+0x4d9/0xaf0 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip6_output+0x1c9/0x650 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:462 [inline]
 ip6_local_out+0x93/0x170 net/ipv6/output_core.c:178
 ip6_send_skb+0x9b/0x2f0 net/ipv6/ip6_output.c:1688
 udp_v6_send_skb+0x4f3/0xf20 net/ipv6/udp.c:1081
 udpv6_sendmsg+0x1eb9/0x2610 net/ipv6/udp.c:1353
 inet_sendmsg+0x116/0x4d0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xc5/0x100 net/socket.c:656
 ___sys_sendmsg+0x349/0x840 net/socket.c:2062
 __sys_sendmmsg+0x129/0x330 net/socket.c:2152
 SYSC_sendmmsg net/socket.c:2183 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c829
RSP: 002b:00007f8e6e013c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004fc3a0 RCX: 000000000045c829
RDX: 00000000000001b1 RSI: 00000000200010c0 RDI: 0000000000000006
RBP: 000000000078c0e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008df R14: 00000000004cb835 R15: 00007f8e6e0146d4

Allocated by task 6840:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15b/0x7c0 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 sock_kmalloc net/core/sock.c:1982 [inline]
 sock_kmalloc+0x75/0xc0 net/core/sock.c:1973
 hash_alloc_result.part.0+0x94/0x110 crypto/algif_hash.c:46
 hash_alloc_result crypto/algif_hash.c:65 [inline]
 hash_recvmsg+0x50e/0x880 crypto/algif_hash.c:206
 ___sys_recvmsg+0x21f/0x4d0 net/socket.c:2221
 __sys_recvmmsg+0x1f3/0x620 net/socket.c:2329
 SYSC_recvmmsg net/socket.c:2405 [inline]
 SyS_recvmmsg+0x125/0x140 net/socket.c:2394
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 6840:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 __sock_kfree_s net/core/sock.c:2001 [inline]
 sock_kzfree_s+0x24/0x50 net/core/sock.c:2015
 hash_free_result crypto/algif_hash.c:64 [inline]
 hash_recvmsg+0x3c8/0x880 crypto/algif_hash.c:231
 ___sys_recvmsg+0x21f/0x4d0 net/socket.c:2221
 __sys_recvmmsg+0x1f3/0x620 net/socket.c:2329
 SYSC_recvmmsg net/socket.c:2405 [inline]
 SyS_recvmmsg+0x125/0x140 net/socket.c:2394
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88809fbe7800
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 18 bytes inside of
 32-byte region [ffff88809fbe7800, ffff88809fbe7820)
The buggy address belongs to the page:
page:ffffea00027ef9c0 count:1 mapcount:0 mapping:ffff88809fbe7000 index:0xffff88809fbe7fc1
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff88809fbe7000 ffff88809fbe7fc1 0000000100000028
raw: ffffea0002a10c60 ffffea000241b4a0 ffff88812fe541c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809fbe7700: 05 fc fc fc fc fc fc fc 00 01 fc fc fc fc fc fc
 ffff88809fbe7780: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc
>ffff88809fbe7800: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc
                         ^
 ffff88809fbe7880: fb fb fb fb fc fc fc fc 05 fc fc fc fc fc fc fc
 ffff88809fbe7900: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================