Date:   Fri, 09 Mar 2018 12:59:04 -0800
From:   syzbot <syzbot+5e82f99b242e7f5e1d18@...kaller.appspotmail.com>
To:     dasaratharaman.chandramouli@...el.com, dledford@...hat.com,
        jgg@...pe.ca, leon@...nel.org, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, parav@...lanox.com,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: general protection fault in ucma_set_ib_path

Hello,

syzbot hit the following crash on upstream commit
1b88accf6a659c46d5c8e68912896f112bf882bb (Thu Mar 8 01:49:33 2018 +0000)
Merge tag 'for_linus' of  
git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

So far this crash happened 2 times on upstream.
C reproducer is attached.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+5e82f99b242e7f5e1d18@...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.

audit: type=1400 audit(1520532856.844:6): avc:  denied  { map } for   
pid=4235 comm="bash" path="/bin/bash" dev="sda1" ino=1457  
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1
audit: type=1400 audit(1520532863.173:7): avc:  denied  { map } for   
pid=4249 comm="syzkaller677323" path="/root/syzkaller677323420" dev="sda1"  
ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
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: 4249 Comm: syzkaller677323 Not tainted 4.16.0-rc4+ #346
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:rdma_cap_opa_ah include/rdma/ib_verbs.h:2777 [inline]
RIP: 0010:ucma_set_ib_path.isra.14+0x26a/0x850  
drivers/infiniband/core/ucma.c:1231
RSP: 0018:ffff8801d3fcf820 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000029
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: 0000000000000148
RBP: ffff8801d3fcfa20 R08: ffffed003a7f9f1e R09: ffffffff867a1b5c
R10: 0000000000000002 R11: ffffed003a7f9f1d R12: ffff8801d3fcf8d0
R13: 1ffff1003a7f9f06 R14: ffff8801b0e3d070 R15: ffff8801b09576c0
FS:  0000000001c43880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005581e954c110 CR3: 00000001b7de6005 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  ucma_set_option_ib drivers/infiniband/core/ucma.c:1254 [inline]
  ucma_set_option_level drivers/infiniband/core/ucma.c:1273 [inline]
  ucma_set_option+0x252/0x4d0 drivers/infiniband/core/ucma.c:1304
  ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1627
  __vfs_write+0xef/0x970 fs/read_write.c:480
  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
  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43fea9
RSP: 002b:00007ffc0b06c988 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fea9
RDX: 000000000000034d RSI: 0000000020001340 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000217 R12: 00000000004017d0
R13: 0000000000401860 R14: 0000000000000000 R15: 0000000000000000
Code: 00 00 48 c1 ea 03 80 3c 02 00 0f 85 0d 05 00 00 49 8b 07 48 ba 00 00  
00 00 00 fc ff df 48 8d b8 48 01 00 00 48 89 f9 48 c1 e9 03 <80> 3c 11 00  
0f 85 54 05 00 00 48 c1 e3 04 48 03 98 48 01 00 00
RIP: rdma_cap_opa_ah include/rdma/ib_verbs.h:2777 [inline] RSP:  
ffff8801d3fcf820
RIP: ucma_set_ib_path.isra.14+0x26a/0x850  
drivers/infiniband/core/ucma.c:1231 RSP: ffff8801d3fcf820
---[ end trace e658861a5e75e206 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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View attachment "raw.log.txt" of type "text/plain" (5950 bytes)

View attachment "repro.syz.txt" of type "text/plain" (620 bytes)

View attachment "repro.c.txt" of type "text/plain" (1868 bytes)

View attachment "config.txt" of type "text/plain" (137392 bytes)

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