BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
IP: [<ffffffff835a67f8>] sock_hold include/net/sock.h:589 [inline]
IP: [<ffffffff835a67f8>] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809
PGD b5f86067 PUD b6d83067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 22132 Comm: syz-executor2 Not tainted 4.4.145-g2241aa9 #78
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801bdf36000 task.stack: ffff8800a7e10000
RIP: 0010:[<ffffffff835a67f8>]  [<ffffffff835a67f8>] sock_hold include/net/sock.h:589 [inline]
RIP: 0010:[<ffffffff835a67f8>]  [<ffffffff835a67f8>] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809
RSP: 0018:ffff8800a7e17b48  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8800b382ac80 RCX: ffffc90002886000
RDX: 1ffff100167055c0 RSI: ffffffff835a08d3 RDI: ffff8800b382ae00
RBP: ffff8800a7e17bb8 R08: ffff8801bdf36900 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8463a1e0 R12: ffff8800af47bc28
R13: ffff8800a7e17cd0 R14: ffff8800af47bb80 R15: ffffffff835a03b0
FS:  00007fc038703700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 0000000099231000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000000 0000000000000000 ffff8800af47bcd8 ffff8800af47bb90
 000005b4000005b4 ffff8800af47bc30 ffff8800af47bcd0 ffff8800b382ad60
 0000000000000000 ffff8800a35c5500 0000000000000000 ffff8800a35c5530
Call Trace:
 [<ffffffff835aabf0>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f23798>] SYSC_connect+0x1b8/0x300 net/socket.c:1557
 [<ffffffff82f260d4>] SyS_connect+0x24/0x30 net/socket.c:1538
 [<ffffffff838c84e5>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: 00 00 48 8d bb 80 01 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 36 06 00 00 48 8b 83 80 01 00 00 <f0> ff 80 80 00 00 00 48 8d 43 20 48 89 c7 48 89 45 b0 e8 e1 13 
RIP  [<ffffffff835a67f8>] sock_hold include/net/sock.h:589 [inline]
RIP  [<ffffffff835a67f8>] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809
 RSP <ffff8800a7e17b48>
CR2: 0000000000000080
binder: BINDER_SET_CONTEXT_MGR already set
binder: 22161:22164 ioctl 40046207 0 returned -16
binder_alloc: 22161: binder_alloc_buf, no vma
binder: 22161:22190 transaction failed 29189/-3, size 0-0 line 3137
---[ end trace e0ce64316bcf24ec ]---