general protection fault in rdma_resolve_route

[syzbot <syzbot+17c13600b3977aa8ef7f@syzkaller.appspotmail.com>]

Hello,

syzbot hit the following crash on upstream commit
a27fc14219f2e3c4a46ba9177b04d9b52c875532 (Mon Apr 16 21:07:39 2018 +0000)
Merge branch 'parisc-4.17-3' of  
git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=17c13600b3977aa8ef7f

So far this crash happened 2 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6198183931674624
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-5914490758943236750
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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Reported-by: syzbot+17c13600b3977aa8ef7f@syzkaller.appspotmail.com
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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: 1 PID: 750 Comm: syz-executor4 Not tainted 4.17.0-rc1+ #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:rdma_cap_ib_sa include/rdma/ib_verbs.h:2840 [inline]
RIP: 0010:rdma_resolve_route+0x134/0x2160 drivers/infiniband/core/cma.c:2668
RSP: 0018:ffff8801b3e87850 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff8801abf92c00 RCX: 0000000000000029
RDX: dffffc0000000000 RSI: 0000000000000004 RDI: 0000000000000148
RBP: ffff8801b3e87a00 R08: ffffed00357f25e5 R09: ffffed00357f25e4
R10: ffffed00357f25e4 R11: ffff8801abf92f23 R12: 1ffff100367d0f12
R13: dffffc0000000000 R14: ffff8801abf92db8 R15: 0000000000000000
FS:  00007f673e752700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000a3eab8 CR3: 00000001b10e7000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  ucma_resolve_route+0x179/0x1c0 drivers/infiniband/core/ucma.c:741
  ucma_write+0x328/0x410 drivers/infiniband/core/ucma.c:1664
  __vfs_write+0x10b/0x880 fs/read_write.c:485
  vfs_write+0x1f8/0x560 fs/read_write.c:549
  ksys_write+0xf9/0x250 fs/read_write.c:598
  __do_sys_write fs/read_write.c:610 [inline]
  __se_sys_write fs/read_write.c:607 [inline]
  __x64_sys_write+0x73/0xb0 fs/read_write.c:607
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455329
RSP: 002b:00007f673e751c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f673e7526d4 RCX: 0000000000455329
RDX: 0000000000000010 RSI: 0000000020000100 RDI: 0000000000000014
RBP: 000000000072c010 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000006c3 R14: 00000000006fd2e8 R15: 0000000000000002
Code: ff df 48 c1 ea 03 80 3c 02 00 0f 85 14 1c 00 00 48 ba 00 00 00 00 00  
fc ff df 48 8b 03 48 8d b8 48 01 00 00 48 89 f9 48 c1 e9 03 <80> 3c 11 00  
0f 85 d7 1b 00 00 45 0f b6 ef 49 c1 e5 04 4c 03 a8
RIP: rdma_cap_ib_sa include/rdma/ib_verbs.h:2840 [inline] RSP:  
ffff8801b3e87850
RIP: rdma_resolve_route+0x134/0x2160 drivers/infiniband/core/cma.c:2668  
RSP: ffff8801b3e87850
---[ end trace c34c2fb6aeff4a19 ]---


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