audit: type=1400 audit(1520088287.164:45): avc:  denied  { map } for  pid=6732 comm="syz-executor0" path="/dev/ppp" dev="devtmpfs" ino=9409 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:ppp_device_t:s0 tclass=chr_file permissive=1
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 6745 Comm: syz-executor6 Not tainted 4.16.0-rc3+ #248
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ip6_xmit+0xc16/0x2260 net/ipv6/ip6_output.c:264
RSP: 0018:ffff8801c11bf4a8 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8801c5ea7340 RCX: ffffffff84ef13fd
RDX: 000000002000a5be RSI: ffffc90004464000 RDI: 0000000100052df6
RBP: ffff8801c11bf718 R08: 1ffff10038bd4e01 R09: ffff8801c11bf668
R10: ffff8801c11bf4a8 R11: ffffed0038237ed4 R12: 0000000100052b26
R13: ffffed0038237ecd R14: 0000000000000040 R15: ffff8801d9288de4
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f77bfb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000008340025 CR3: 00000001c5ec2005 CR4: 00000000001626e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
 l2tp_xmit_core net/l2tp/l2tp_core.c:1096 [inline]
 l2tp_xmit_skb+0x105f/0x1410 net/l2tp/l2tp_core.c:1191
 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
 sock_write_iter+0x31a/0x5d0 net/socket.c:909
 call_write_iter include/linux/fs.h:1781 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x684/0x970 fs/read_write.c:482
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fc3c99
RSP: 002b:00000000f77bf09c EFLAGS: 00000286 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000014 RCX: 0000000020604000
RDX: 0000000000000008 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: 4d 8b a4 24 18 01 00 00 4d 85 e4 74 67 e8 43 e0 81 fc 49 8d bc 24 d0 02 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 5b 13 00 00 48 8b 95 e0 fd ff ff 48 b8 00 00 
RIP: ip6_xmit+0xc16/0x2260 net/ipv6/ip6_output.c:264 RSP: ffff8801c11bf4a8
---[ end trace b4128ca33d8cdc51 ]---
Kernel panic - not syncing: Fatal exception in interrupt
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..