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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+0x1f76/0x2260 net/ipv6/ip6_output.c:264
Read of size 8 at addr ffff8801cb887218 by task syz-executor2/5673

CPU: 1 PID: 5673 Comm: syz-executor2 Not tainted 4.16.0-rc4+ #254
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+0x23c/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+0x1f76/0x2260 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:1053 [inline]
 l2tp_xmit_skb+0x105f/0x1410 net/l2tp/l2tp_core.c:1148
 pppol2tp_sendmsg+0x470/0x670 net/l2tp/l2tp_ppp.c:341
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:639
 ___sys_sendmsg+0x767/0x8b0 net/socket.c:2047
 __sys_sendmsg+0xe5/0x210 net/socket.c:2081
 SYSC_sendmsg net/socket.c:2092 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2088
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x453e69
RSP: 002b:00007faaf0e7bc68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007faaf0e7c6d4 RCX: 0000000000453e69
RDX: 0000000000000081 RSI: 000000002037ffc8 RDI: 0000000000000016
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000004c3 R14: 00000000006f72e8 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 ffff8801cb887200
 which belongs to the cache ip_dst_cache of size 160
The buggy address is located 24 bytes inside of
 160-byte region [ffff8801cb887200, ffff8801cb8872a0)
The buggy address belongs to the page:
page:ffffea00072e21c0 count:1 mapcount:0 mapping:ffff8801cb887000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801cb887000 0000000000000000 0000000100000010
raw: ffffea00072ffee0 ffff8801d5b8cb48 ffff8801d5b8b800 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cb887100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cb887180: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801cb887200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                            ^
 ffff8801cb887280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801cb887300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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