Subject: general protection fault in smc_set_keepalive

From: syzbot <[email-masked]>
Date: Tue, 24 Apr 2018 18:40:02 -0700

Hello,

syzbot hit the following crash on net-next commit
9c20b9372fbaf6f7d4c05f5f925806a7928f0c73 (Tue Apr 24 03:08:41 2018 +0000)
net: fib_rules: fix l3mdev netlink attr processing
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=cf9012c597c8379d535c

So far this crash happened 2 times on net-next.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=4775309383565312
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=4978230683500544
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=4770663504019456
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-2918904850634584293
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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Reported-by: [email-masked]
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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: 0 PID: 4455 Comm: syz-executor060 Not tainted 4.17.0-rc1+ #17
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:smc_set_keepalive+0x4e/0xd0 net/smc/af_smc.c:59
RSP: 0018:ffff8801ced8fa68 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff85d72bcb
RDX: 0000000000000004 RSI: ffffffff873f0a94 RDI: 0000000000000020
RBP: ffff8801ced8fa80 R08: ffff8801b67e44c0 R09: 0000000000000006
R10: ffff8801b67e44c0 R11: 0000000000000000 R12: ffff8801b6bff7c0
R13: 0000000000000001 R14: 0000000000000003 R15: ffff8801aee2b540
FS:  00000000009e4880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000040 CR3: 00000001b6e75000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  sock_setsockopt+0x14e2/0x1fe0 net/core/sock.c:801
  __sys_setsockopt+0x2df/0x390 net/socket.c:1899
  __do_sys_setsockopt net/socket.c:1914 [inline]
  __se_sys_setsockopt net/socket.c:1911 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fcf9
RSP: 002b:00007ffe62977a78 EFLAGS: 00000217 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fcf9
RDX: 0000000000000009 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000004 R09: 00000000004002c8
R10: 0000000020000040 R11: 0000000000000217 R12: 0000000000401620
R13: 00000000004016b0 R14: 0000000000000000 R15: 0000000000000000
Code: ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 78 48 8b 9b 50 04 00 00 48  
b8 00 00 00 00 00 fc ff df 48 8d 7b 20 48 89 fa 48 c1 ea 03 <80> 3c 02 00  
75 6b 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 20 48
RIP: smc_set_keepalive+0x4e/0xd0 net/smc/af_smc.c:59 RSP: ffff8801ced8fa68
---[ end trace a76f9ed0fb111068 ]---

---
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