BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: __rb_insert lib/rbtree.c:126 [inline]
IP: rb_insert_color+0x17/0x190 lib/rbtree.c:452
PGD 1d94e4067 P4D 1d94e4067 PUD 20dae2067 PMD 0 
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 25937 Comm: syz-executor6 Not tainted 4.15.0-rc3-next-20171214+ #67
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__rb_insert lib/rbtree.c:126 [inline]
RIP: 0010:rb_insert_color+0x17/0x190 lib/rbtree.c:452
RSP: 0018:ffffc90000db7d38 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801de889080 RCX: ffffffff81631d64
RDX: ffff8801dfae5008 RSI: ffffffff83fc3860 RDI: ffff8801de889088
RBP: ffffc90000db7d38 R08: 0000000000000001 R09: 0000000000000004
R10: ffffc90000db7cb8 R11: 0000000000000004 R12: 0000000000000000
R13: ffff8801dfae5010 R14: ffffffff83fc3860 R15: ffff8801dfae5008
FS:  00007fdc6d231700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 00000001df82b000 CR4: 00000000001426f0
Call Trace:
 key_alloc_serial security/keys/key.c:170 [inline]
 key_alloc+0x54c/0x5b0 security/keys/key.c:319
 keyring_alloc+0x4d/0xb0 security/keys/keyring.c:503
 install_process_keyring_to_cred.part.3+0x38/0x80 security/keys/process_keys.c:192
 install_process_keyring_to_cred security/keys/process_keys.c:634 [inline]
 install_process_keyring security/keys/process_keys.c:217 [inline]
 lookup_user_key+0x4ed/0x7c0 security/keys/process_keys.c:574
 SYSC_add_key security/keys/keyctl.c:114 [inline]
 SyS_add_key+0xec/0x260 security/keys/keyctl.c:62
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a39
RSP: 002b:00007fdc6d230c58 EFLAGS: 00000212 ORIG_RAX: 00000000000000f8
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452a39
RDX: 0000000020000f92 RSI: 0000000020002000 RDI: 0000000020000ff6
RBP: 000000000000049b R08: fffffffffffffffe R09: 0000000000000000
R10: 000000000000006e R11: 0000000000000212 R12: 00000000006f4f28
R13: 00000000ffffffff R14: 00007fdc6d2316d4 R15: 0000000000000000
Code: 48 85 d2 75 eb 5d c3 31 c0 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 8b 17 48 89 e5 48 85 d2 0f 84 4c 01 00 00 48 8b 02 a8 01 75 5e <48> 8b 48 08 49 89 c0 48 39 d1 74 54 48 85 c9 74 09 f6 01 01 0f 
RIP: __rb_insert lib/rbtree.c:126 [inline] RSP: ffffc90000db7d38
RIP: rb_insert_color+0x17/0x190 lib/rbtree.c:452 RSP: ffffc90000db7d38
CR2: 0000000000000008
---[ end trace 5b808e732989dcfd ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..