Date:   Tue, 02 Jan 2018 10:58:01 -0800
From:   syzbot <syzbot+e432865c29eb4c48c142@...kaller.appspotmail.com>
To:     Jason@...c4.com, akpm@...ux-foundation.org,
        alexander.deucher@....com, avagin@...nvz.org,
        chris@...is-wilson.co.uk, davem@...emloft.net, dsahern@...il.com,
        edumazet@...gle.com, elena.reshetova@...el.com,
        gregkh@...uxfoundation.org, herbert@...dor.apana.org.au,
        johannes.berg@...el.com, linux-kernel@...r.kernel.org,
        lucien.xin@...il.com, mchehab@...nel.org, netdev@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: general protection fault in __netlink_ns_capable

Hello,

syzkaller hit the following crash on  
75aa5540627fdb3d8f86229776ea87f995275351
git://git.cmpxchg.org/linux-mmots.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e432865c29eb4c48c142@...kaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

netlink: 3 bytes leftover after parsing attributes in process  
`syzkaller140561'.
netlink: 3 bytes leftover after parsing attributes in process  
`syzkaller140561'.
netlink: 3 bytes leftover after parsing attributes in process  
`syzkaller140561'.
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 3149 Comm: syzkaller140561 Not tainted 4.15.0-rc4-mm1+ #47
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__netlink_ns_capable+0x8b/0x120 net/netlink/af_netlink.c:868
RSP: 0018:ffff8801c880f348 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8443f900
RDX: 000000000000007b RSI: ffffffff86510f40 RDI: 00000000000003d8
RBP: ffff8801c880f360 R08: 0000000000000000 R09: 1ffff10039101e4f
R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff86510f40
R13: 000000000000000c R14: 0000000000000004 R15: 0000000000000011
FS:  0000000001a1a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020151000 CR3: 00000001c9511005 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  netlink_ns_capable+0x26/0x30 net/netlink/af_netlink.c:886
  get_target_net+0x9d/0x120 net/core/rtnetlink.c:1765
  rtnl_dump_ifinfo+0x2e5/0xee0 net/core/rtnetlink.c:1806
  netlink_dump+0x48c/0xce0 net/netlink/af_netlink.c:2222
  __netlink_dump_start+0x4f0/0x6d0 net/netlink/af_netlink.c:2319
  netlink_dump_start include/linux/netlink.h:214 [inline]
  rtnetlink_rcv_msg+0x7f0/0xb10 net/core/rtnetlink.c:4485
  netlink_rcv_skb+0x21e/0x460 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+0x4be/0x6a0 net/netlink/af_netlink.c:1334
  netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1897
  sock_sendmsg_nosec net/socket.c:628 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:638
  sock_write_iter+0x31a/0x5d0 net/socket.c:907
  call_write_iter include/linux/fs.h:1776 [inline]
  new_sync_write fs/read_write.c:469 [inline]
  __vfs_write+0x684/0x970 fs/read_write.c:482
  vfs_write+0x189/0x510 fs/read_write.c:544
  SYSC_write fs/read_write.c:589 [inline]
  SyS_write+0xef/0x220 fs/read_write.c:581
  entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x43fd49
RSP: 002b:00007ffc7fb92238 EFLAGS: 00000203 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 000000000043fd49
RDX: 000000000000001f RSI: 0000000020151000 RDI: 0000000000000005
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000203 R12: 00000000004016b0
R13: 0000000000401740 R14: 0000000000000000 R15: 0000000000000000
Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 95 00 00 00 48 8b 5b 18 48 b8 00 00  
00 00 00 fc ff df 48 8d bb d8 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00  
0f 85 80 00 00 00 48 8b 9b d8 03 00 00 48 b8 00 00
RIP: __netlink_ns_capable+0x8b/0x120 net/netlink/af_netlink.c:868 RSP:  
ffff8801c880f348
---[ end trace d7574f6bd3eea534 ]---


---
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