netlink: 8 bytes leftover after parsing attributes in process `syz-executor4'.
------------[ cut here ]------------
kernel BUG at net/l2tp/l2tp_ppp.c:176!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 5347 Comm: syz-executor6 Not tainted 4.15.0-rc8+ #201
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:pppol2tp_sock_to_session net/l2tp/l2tp_ppp.c:176 [inline]
RIP: 0010:pppol2tp_sendmsg+0x512/0x670 net/l2tp/l2tp_ppp.c:304
RSP: 0018:ffff8801cc347438 EFLAGS: 00010216
RAX: 0000000000010000 RBX: ffff8801c13309c0 RCX: ffffffff8506b652
RDX: 000000000000025b RSI: ffffc90004e56000 RDI: ffff8801c1330da0
RBP: ffff8801cc3474a8 R08: 0000000000000000 R09: 1ffff10039868e17
R10: 0000000000000003 R11: 0000000000000001 R12: ffff8801c2e8edc0
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
FS:  00007f6241bd8700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000a2fa38 CR3: 00000001c19f3005 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 sock_sendmsg_nosec net/socket.c:630 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:640
 kernel_sendmsg+0x47/0x60 net/socket.c:648
 sock_no_sendpage+0x1cc/0x280 net/core/sock.c:2581
 kernel_sendpage+0xbf/0xe0 net/socket.c:3351
 kcm_write_msgs+0x404/0x1b80 net/kcm/kcmsock.c:646
 kcm_sendmsg+0x148d/0x22d0 net/kcm/kcmsock.c:1035
 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: 0033:0x452ee9
RSP: 002b:00007f6241bd7c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452ee9
RDX: 0000000000000000 RSI: 0000000020dc2953 RDI: 0000000000000016
RBP: 000000000000038e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f45f0
R13: 00000000ffffffff R14: 00007f6241bd86d4 R15: 000000000000000c
Code: e5 7c 69 fc 48 8b 7d d0 e8 ec 14 55 fd 84 c0 74 0d e8 d3 7c 69 fc 48 89 df e8 bb 5f 2b ff 41 bd f7 ff ff ff eb 86 e8 be 7c 69 fc <0f> 0b 41 bd 95 ff ff ff e9 74 ff ff ff e8 5c 86 a1 fc e9 77 fb 
RIP: pppol2tp_sock_to_session net/l2tp/l2tp_ppp.c:176 [inline] RSP: ffff8801cc347438
RIP: pppol2tp_sendmsg+0x512/0x670 net/l2tp/l2tp_ppp.c:304 RSP: ffff8801cc347438
---[ end trace bf4f1e7536726eed ]---