Date:   Fri, 09 Mar 2018 12:59:04 -0800
From:   syzbot <syzbot+28b14b75b4a9314ead4a@...kaller.appspotmail.com>
To:     dasaratharaman.chandramouli@...el.com, dledford@...hat.com,
        jgg@...pe.ca, leonro@...lanox.com, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, markb@...lanox.com, monis@...lanox.com,
        parav@...lanox.com, syzkaller-bugs@...glegroups.com
Subject: KASAN: stack-out-of-bounds Read in rdma_bind_addr

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+28b14b75b4a9314ead4a@...kaller.appspotmail.com
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If you forward the report, please keep this part and the footer.

audit: type=1400 audit(1520533676.373:6): avc:  denied  { map } for   
pid=4262 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(1520533682.727:7): avc:  denied  { map } for   
pid=4276 comm="syzkaller727467" path="/root/syzkaller727467593" 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
==================================================================
BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:345  
[inline]
BUG: KASAN: stack-out-of-bounds in rdma_bind_addr+0x156/0x1b50  
drivers/infiniband/core/cma.c:3359
Read of size 48 at addr ffff8801cb03fa50 by task syzkaller727467/4276

CPU: 1 PID: 4276 Comm: syzkaller727467 Not tainted 4.16.0-rc4+ #346
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x24d lib/dump_stack.c:53
  print_address_description+0x73/0x250 mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report+0x23c/0x360 mm/kasan/report.c:412
  check_memory_region_inline mm/kasan/kasan.c:260 [inline]
  check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
  memcpy+0x23/0x50 mm/kasan/kasan.c:302
  memcpy include/linux/string.h:345 [inline]
  rdma_bind_addr+0x156/0x1b50 drivers/infiniband/core/cma.c:3359
  ucma_bind_ip+0x10a/0x190 drivers/infiniband/core/ucma.c:633
  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: 0033:0x43fdb9
RSP: 002b:00007ffc27556e48 EFLAGS: 00000213 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fdb9
RDX: 0000000000000024 RSI: 0000000020000bc0 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000213 R12: 00000000004016e0
R13: 0000000000401770 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea00072c0fc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea00072c0101 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801cb03f900: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2
  ffff8801cb03f980: f2 f2 f2 f2 f2 f2 04 f2 f2 f2 f3 f3 f3 f3 00 00
> ffff8801cb03fa00: 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 f2 f2
                                                              ^
  ffff8801cb03fa80: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1
  ffff8801cb03fb00: f1 f1 f1 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00
==================================================================


---
This bug is generated by a dumb bot. It may contain errors.
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View attachment "repro.syz.txt" of type "text/plain" (598 bytes)

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