==================================================================
BUG: KASAN: global-out-of-bounds in ip6_xmit+0x1f80/0x2260 net/ipv6/ip6_output.c:264
Read of size 8 at addr ffffffff885e2950 by task syz-executor5/10509

CPU: 1 PID: 10509 Comm: syz-executor5 Not tainted 4.16.0-rc4+ #264
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+0x178/0x250 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_xmit+0x1f80/0x2260 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
 SYSC_sendto+0x361/0x5c0 net/socket.c:1748
 SyS_sendto+0x40/0x50 net/socket.c:1716
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x453e69
RSP: 002b:00007f71fd3c3c68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f71fd3c46d4 RCX: 0000000000453e69
RDX: 000000000000100b RSI: 0000000020001180 RDI: 0000000000000014
RBP: 000000000072bea0 R08: 00000000200021c0 R09: 0000000000000080
R10: 0000000000040001 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000004ca R14: 00000000006f7390 R15: 0000000000000000

The buggy address belongs to the variable:
 __key.41867+0x10/0x40

Memory state around the buggy address:
 ffffffff885e2800: 00 fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
 ffffffff885e2880: 00 00 00 fa fa fa fa fa 00 fa fa fa fa fa fa fa
>ffffffff885e2900: 00 fa fa fa fa fa fa fa 00 fa fa fa fa fa fa fa
                                                 ^
 ffffffff885e2980: 00 fa fa fa fa fa fa fa 00 fa fa fa fa fa fa fa
 ffffffff885e2a00: 00 fa fa fa fa fa fa fa 00 fa fa fa fa fa fa fa
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 10509 Comm: syz-executor5 Tainted: G    B            4.16.0-rc4+ #264
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
 panic+0x1e4/0x41c kernel/panic.c:183
 kasan_end_report+0x50/0x50 mm/kasan/report.c:180
 kasan_report_error mm/kasan/report.c:359 [inline]
 kasan_report+0x149/0x360 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 ip6_xmit+0x1f80/0x2260 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
 SYSC_sendto+0x361/0x5c0 net/socket.c:1748
 SyS_sendto+0x40/0x50 net/socket.c:1716
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x453e69
RSP: 002b:00007f71fd3c3c68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f71fd3c46d4 RCX: 0000000000453e69
RDX: 000000000000100b RSI: 0000000020001180 RDI: 0000000000000014
RBP: 000000000072bea0 R08: 00000000200021c0 R09: 0000000000000080
R10: 0000000000040001 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000004ca R14: 00000000006f7390 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..