BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 IP: [] sock_hold include/net/sock.h:589 [inline] IP: [] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809 PGD 1cce7c067 PUD 1caeda067 PMD 0 Oops: 0002 [#1] PREEMPT SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 11243 Comm: syz-executor4 Not tainted 4.4.153-g5e24b4e #90 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800b53a8000 task.stack: ffff8800a2248000 RIP: 0010:[] [] sock_hold include/net/sock.h:589 [inline] RIP: 0010:[] [] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809 RSP: 0018:ffff8800a224fb48 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8800b2f6c780 RCX: ffffc90007872000 RDX: 1ffff100165ed920 RSI: ffffffff835a4c93 RDI: ffff8800b2f6c900 RBP: ffff8800a224fbb8 R08: 000000000000000a R09: 000000000000ffff R10: ffffed0017241c18 R11: ffffffff8463a200 R12: ffff8800b920e0a8 R13: ffff8800a224fcd0 R14: ffff8800b920e000 R15: ffffffff835a38c0 FS: 00007f37c4f46700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000080 CR3: 00000001d02ff000 CR4: 00000000001606f0 Stack: ffffffff81140aba ffff8800b2f6c7a0 ffff8800b920e158 ffff8800b920e010 ffffffff838cc1e0 ffff8800b920e0b0 ffff8800b920e150 ffff8800b2f6c860 ffffffff00000000 ffff8800b3e4c400 0000000000000000 ffff8800b3e4c430 Call Trace: [] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725 [] SYSC_connect+0x1b8/0x300 net/socket.c:1570 [] SyS_connect+0x24/0x30 net/socket.c:1551 [] 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 ff 80 80 00 00 00 48 8d 43 20 48 89 c7 48 89 45 b0 e8 f1 13 RIP [] sock_hold include/net/sock.h:589 [inline] RIP [] l2tp_session_create+0x948/0x1030 net/l2tp/l2tp_core.c:1809 RSP CR2: 0000000000000080 ---[ end trace f08e57f786491065 ]---