audit: type=1400 audit(1520163932.731:23): avc:  denied  { create } for  pid=6010 comm="syz-executor2" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_crypto_socket permissive=1
==================================================================
netlink: 80 bytes leftover after parsing attributes in process `syz-executor0'.
BUG: KASAN: use-after-free in inet_shutdown+0x2d4/0x350 net/ipv4/af_inet.c:818
Read of size 4 at addr ffff8801ce3b2600 by task syz-executor6/6024

CPU: 1 PID: 6024 Comm: syz-executor6 Not tainted 4.16.0-rc2+ #250
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+0x194/0x24d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 inet_shutdown+0x2d4/0x350 net/ipv4/af_inet.c:818
 pppol2tp_session_close+0x92/0xf0 net/l2tp/l2tp_ppp.c:430
 l2tp_tunnel_closeall+0x305/0x410 net/l2tp/l2tp_core.c:1285
 l2tp_udp_encap_destroy+0x95/0x100 net/l2tp/l2tp_core.c:1308
 udpv6_destroy_sock+0x161/0x190 net/ipv6/udp.c:1407
 sk_common_release+0x6b/0x2f0 net/core/sock.c:3000
 udp_lib_close+0x15/0x20 include/net/udp.h:203
 inet_release+0xed/0x1c0 net/ipv4/af_inet.c:427
 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:435
 sock_release+0x8d/0x1e0 net/socket.c:594
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6e5/0x940 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x453d69
RSP: 002b:00007f617b356c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f617b3576d4 RCX: 0000000000453d69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000014
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000052 R14: 00000000006f0850 R15: 0000000000000000

Allocated by task 6024:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3541
 sock_alloc_inode+0x70/0x300 net/socket.c:243
 alloc_inode+0x65/0x180 fs/inode.c:209
 new_inode_pseudo+0x69/0x190 fs/inode.c:890
 sock_alloc+0x41/0x270 net/socket.c:564
 __sock_create+0x148/0x850 net/socket.c:1249
 sock_create net/socket.c:1325 [inline]
 SYSC_socket net/socket.c:1355 [inline]
 SyS_socket+0xeb/0x1d0 net/socket.c:1335
 do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 6040:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3743
 sock_destroy_inode+0x56/0x70 net/socket.c:273
 destroy_inode+0x15d/0x200 fs/inode.c:266
 evict+0x57e/0x920 fs/inode.c:570
 iput_final fs/inode.c:1515 [inline]
 iput+0x7b9/0xaf0 fs/inode.c:1542
 dentry_unlink_inode+0x4b0/0x5e0 fs/dcache.c:371
 __dentry_kill+0x3de/0x700 fs/dcache.c:575
 dentry_kill fs/dcache.c:616 [inline]
 dput.part.21+0x6fb/0x830 fs/dcache.c:826
 dput+0x1f/0x30 fs/dcache.c:790
 __fput+0x51c/0x7e0 fs/file_table.c:227
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6e5/0x940 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801ce3b2600
 which belongs to the cache sock_inode_cache of size 992
The buggy address is located 0 bytes inside of
 992-byte region [ffff8801ce3b2600, ffff8801ce3b29e0)
The buggy address belongs to the page:
page:ffffea000738ec80 count:1 mapcount:0 mapping:ffff8801ce3b2180 index:0xffff8801ce3b2ffd
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801ce3b2180 ffff8801ce3b2ffd 0000000100000003
raw: ffffea0007246360 ffffea000738ed20 ffff8801d9bec380 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ce3b2500: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff8801ce3b2580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801ce3b2600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801ce3b2680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801ce3b2700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================