audit: type=1400 audit(1516243865.528:9): avc:  denied  { sys_chroot } for  pid=3784 comm="syzkaller944646" capability=18  scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1
==================================================================
BUG: KASAN: slab-out-of-bounds in ip6_dst_idev include/net/ip6_fib.h:192 [inline]
BUG: KASAN: slab-out-of-bounds in ip6_xmit+0x1ce9/0x2090 net/ipv6/ip6_output.c:264
Read of size 8 at addr ffff8801bfcf8318 by task syzkaller944646/3784

CPU: 1 PID: 3784 Comm: syzkaller944646 Not tainted 4.15.0-rc7-mm1+ #56
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+0x194/0x257 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_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 ip6_dst_idev include/net/ip6_fib.h:192 [inline]
 ip6_xmit+0x1ce9/0x2090 net/ipv6/ip6_output.c:264
 inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
 l2tp_xmit_core net/l2tp/l2tp_core.c:1099 [inline]
 l2tp_xmit_skb+0x105f/0x1410 net/l2tp/l2tp_core.c:1194
 pppol2tp_sendmsg+0x470/0x670 net/l2tp/l2tp_ppp.c:341
 sock_sendmsg_nosec net/socket.c:630 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:640
 ___sys_sendmsg+0x767/0x8b0 net/socket.c:2020
 __sys_sendmsg+0xe5/0x210 net/socket.c:2054
 SYSC_sendmsg net/socket.c:2065 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2061
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x446f29
RSP: 002b:00000000007eff68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004a8ef4 RCX: 0000000000446f29
RDX: 0000000000000081 RSI: 000000002037ffc8 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffebafecf98
R13: 00000000004043a0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8801bfcf8300
 which belongs to the cache ip_dst_cache of size 168
The buggy address is located 24 bytes inside of
 168-byte region [ffff8801bfcf8300, ffff8801bfcf83a8)
The buggy address belongs to the page:
page:ffffea0006ff3e00 count:1 mapcount:0 mapping:ffff8801bfcf8000 index:0xffff8801bfcf8b00
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801bfcf8000 ffff8801bfcf8b00 0000000100000009
raw: ffff8801d6ff7738 ffffea0007331ea0 ffff8801d6ffa680 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bfcf8200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801bfcf8280: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff8801bfcf8300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                            ^
 ffff8801bfcf8380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801bfcf8400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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