==================================================================
BUG: KASAN: slab-out-of-bounds in ip6_dst_idev include/net/ip6_fib.h:141 [inline]
BUG: KASAN: slab-out-of-bounds in ip6_xmit+0x177c/0x1a00 net/ipv6/ip6_output.c:237
Read of size 8 at addr ffff8801d6778298 by task syz-executor2/5867

CPU: 0 PID: 5867 Comm: syz-executor2 Not tainted 4.4.152-ge5c5f1f #89
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 8029120c8f68ebfd ffff8801bde9f5c8 ffffffff81e15fed
 ffffea000759de00 ffff8801d6778298 0000000000000000 ffff8801d6778298
 0000000000001000 ffff8801bde9f600 ffffffff8151b489 ffff8801d6778298
Call Trace:
 [<ffffffff81e15fed>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e15fed>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8151b489>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff8151b7a8>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8151b7a8>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814fe734>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff83435efc>] ip6_dst_idev include/net/ip6_fib.h:141 [inline]
 [<ffffffff83435efc>] ip6_xmit+0x177c/0x1a00 net/ipv6/ip6_output.c:237
 [<ffffffff834f60c5>] inet6_csk_xmit+0x245/0x490 net/ipv6/inet6_connection_sock.c:176
 [<ffffffff835a570c>] l2tp_xmit_core net/l2tp/l2tp_core.c:1084 [inline]
 [<ffffffff835a570c>] l2tp_xmit_skb+0xb9c/0xe80 net/l2tp/l2tp_core.c:1179
 [<ffffffff835b1c60>] pppol2tp_sendmsg+0x4e0/0x7d0 net/l2tp/l2tp_ppp.c:355
 [<ffffffff82f2727c>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff82f2727c>] sock_sendmsg+0xcc/0x110 net/socket.c:648
 [<ffffffff82f28a41>] ___sys_sendmsg+0x441/0x880 net/socket.c:1975
 [<ffffffff82f2b02e>] __sys_sendmmsg+0x12e/0x2e0 net/socket.c:2060
 [<ffffffff82f2b215>] SYSC_sendmmsg net/socket.c:2090 [inline]
 [<ffffffff82f2b215>] SyS_sendmmsg+0x35/0x60 net/socket.c:2085
 [<ffffffff838cc565>] entry_SYSCALL_64_fastpath+0x22/0x9e

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8801d6778280
 which belongs to the cache ip_dst_cache of size 208
The buggy address is located 24 bytes inside of
 208-byte region [ffff8801d6778280, ffff8801d6778350)
The buggy address belongs to the page:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5912 at kernel/locking/lockdep.c:3190 __lock_acquire+0x265f/0x5270 kernel/locking/lockdep.c:3190()
DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)