BUG: unable to handle kernel NULL pointer dereference in strlen

Hello,

syzkaller hit the following crash on 6084b576dca2e898f5c101baef151f7bfdbb606d
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

Unfortunately, I don't have any reproducer for this bug yet.


netlink: 1 bytes leftover after parsing attributes in process `syz-executor5'.
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: strlen+0x0/0x30 lib/string.c:255
PGD 1fa2a3067 P4D 1fa2a3067 PUD 2156db067 PMD 0
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 25068 Comm: syz-executor5 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:strlen+0x0/0x30 lib/string.c:255
RSP: 0018:ffffc90000f63728 EFLAGS: 00010202
RAX: 0000000000010000 RBX: ffff880215647500 RCX: ffffffff820f1e86
RDX: 0000000000003b6e RSI: ffffc90004536000 RDI: 0000000000000010
RBP: ffffc90000f637a8 R08: 0000000000000000 R09: ffff88020d91707d
R10: ffffc90000f636b8 R11: 0000000000000002 R12: ffff8801fba87000
R13: 0000000000000010 R14: 0000000000000000 R15: ffff88020d917000
FS:  00007f7abdffd700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000010 CR3: 000000020f0fe005 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 rtnl_dump_ifinfo+0x37c/0x570 net/core/rtnetlink.c:1834
 netlink_dump+0x14e/0x360 net/netlink/af_netlink.c:2222
 __netlink_dump_start+0x1bb/0x210 net/netlink/af_netlink.c:2319
 netlink_dump_start include/linux/netlink.h:214 [inline]
 rtnetlink_rcv_msg+0x44f/0x5d0 net/core/rtnetlink.c:4485
 netlink_rcv_skb+0x92/0x160 net/netlink/af_netlink.c:2441
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4540
 netlink_unicast_kernel net/netlink/af_netlink.c:1308 [inline]
 netlink_unicast+0x1d4/0x290 net/netlink/af_netlink.c:1334
 netlink_sendmsg+0x345/0x470 net/netlink/af_netlink.c:1897
 sock_sendmsg_nosec net/socket.c:636 [inline]
 sock_sendmsg+0x51/0x70 net/socket.c:646
 sock_write_iter+0xa4/0x100 net/socket.c:915
 call_write_iter include/linux/fs.h:1776 [inline]
 do_iter_readv_writev+0x17d/0x1f0 fs/read_write.c:653
 do_iter_write+0xbc/0x210 fs/read_write.c:932
 vfs_writev+0xa1/0x120 fs/read_write.c:977
 do_writev+0x5e/0x100 fs/read_write.c:1012
 SYSC_writev fs/read_write.c:1085 [inline]
 SyS_writev+0x27/0x30 fs/read_write.c:1082
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a09
RSP: 002b:00007f7abdffcc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452a09
RDX: 0000000000000001 RSI: 00000000206f6000 RDI: 0000000000000013
RBP: 000000000000056f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f5308
R13: 00000000ffffffff R14: 00007f7abdffd6d4 R15: 0000000000000000
Code: 89 f8 48 89 fa 48 89 e5 74 09 48 83 c2 01 80 3a 00 75 f7 48 83 c6 01 0f b6 4e ff 48 83 c2 01 84 c9 88 4a ff 75 ed 5d c3 0f 1f 00 <80> 3f 00 55 48 89 e5 74 14 48 89 f8 48 83 c7 01 80 3f 00 75 f7
RIP: strlen+0x0/0x30 lib/string.c:255 RSP: ffffc90000f63728
CR2: 0000000000000010
---[ end trace 72499b0f3e5056d0 ]---


---
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