KASAN: stack-out-of-bounds Read in rdma_bind_addr (2)

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
0b412605ef5f5c64b31f19e2910b1d5eba9929c3 (Thu Mar 29 01:07:23 2018 +0000)
Merge tag 'drm-fixes-for-v4.16-rc8' of  
git://people.freedesktop.org/~airlied/linux
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=4b6afe4bdd99cb99e664

So far this crash happened 4 times on upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6021023174492160
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=6269942299099136
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6347752745205760
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-8440362230543204781
compiler: gcc (GCC) 7.1.1 20170620

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Reported-by: syzbot+4b6afe4bdd99cb99e664@xxxxxxxxxxxxxxxxxxxxxxxxx
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==================================================================
BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:345  
[inline]
BUG: KASAN: stack-out-of-bounds in rdma_bind_addr+0x13b/0x1d60  
drivers/infiniband/core/cma.c:3361
Read of size 48 at addr ffff8801af717a50 by task syzkaller366236/4421

CPU: 0 PID: 4421 Comm: syzkaller366236 Not tainted 4.16.0-rc7+ #5
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+0x13b/0x1d60 drivers/infiniband/core/cma.c:3361
 ucma_bind_ip+0x10a/0x190 drivers/infiniband/core/ucma.c:639
 ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1649
 __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: 0033:0x43fdd9
RSP: 002b:00007ffc69ab4bb8 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fdd9
RDX: 0000000000000090 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000217 R12: 0000000000401700
R13: 0000000000401790 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006bdc5c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea0006bd0101 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801af717900: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2
 ffff8801af717980: f2 f2 f2 f2 f2 f2 04 f2 f2 f2 f3 f3 f3 f3 00 00
> ffff8801af717a00: 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 f2 f2
                                                             ^
 ffff8801af717a80: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1
 ffff8801af717b00: f1 f1 f1 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00
==================================================================


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