Subject: BUG: unable to handle kernel NULL pointer dereference in inet6_fill_ifinfo

From: syzbot <[email-masked]>
Date: Mon, 18 Dec 2017 23:54:00 -0800

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.

BUG: unable to handle kernel NULL pointer dereference at 000000000000022c
IP: inet6_fill_ifinfo+0x8e/0x2c0 net/ipv6/addrconf.c:5357
PGD 1dffd8067 P4D 1dffd8067 PUD 1dc705067 PMD 0
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 27870 Comm: syz-executor2 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:inet6_fill_ifinfo+0x8e/0x2c0 net/ipv6/addrconf.c:5357
RSP: 0018:ffffc90000f53ae0 EFLAGS: 00010216
RAX: 000000000000000a RBX: ffff88021433b300 RCX: ffffffff8224ba71
RDX: 0000000000000818 RSI: ffffc9000457f000 RDI: 0000000000000000
RBP: ffffc90000f53b18 R08: 0000000000000010 R09: ffff8801dac27ae0
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8801dfaf5c00 R14: ffff8801dac27ac0 R15: 0000000000000002
FS:  00007f0fb6e3b700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000022c CR3: 0000000213560000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
  inet6_dump_ifinfo+0x1ea/0x2d0 net/ipv6/addrconf.c:5411
  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
  SYSC_sendto+0x17f/0x1d0 net/socket.c:1727
  SyS_sendto+0x40/0x50 net/socket.c:1695
  entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a39
RSP: 002b:00007f0fb6e3ac58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452a39
RDX: 0000000000000012 RSI: 0000000020919000 RDI: 0000000000000013
RBP: 0000000000000553 R08: 0000000020000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f6068
R13: 00000000ffffffff R14: 00007f0fb6e3b6d4 R15: 0000000000000000
Code: b8 10 00 00 00 48 89 df e8 d0 b2 ee ff 48 85 c0 49 89 c6 0f 84 c5 01  
00 00 e8 cf e8 06 ff b8 0a 00 00 00 4c 89 e7 66 41 89 46 10 <41> 0f b7 84  
24 2c 02 00 00 66 41 89 46 12 41 8b 84 24 08 01 00
RIP: inet6_fill_ifinfo+0x8e/0x2c0 net/ipv6/addrconf.c:5357 RSP:  
ffffc90000f53ae0
CR2: 000000000000022c
---[ end trace bb449c11e1e11a3c ]---

---
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