KASAN: global-out-of-bounds Read in fb_pad_aligned_buffer

[syzbot]

syzbot has bisected this bug to:

commit 2de50e9674fc4ca3c6174b04477f69eb26b4ee31
Author: Russell Currey <ruscur at russell.cc>
Date:   Mon Feb 8 04:08:20 2016 +0000

     powerpc/powernv: Remove support for p5ioc2

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13ea0aeae00000
start commit:   9455d25f Merge tag 'ntb-5.5' of git://github.com/jonmason/..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=101a0aeae00000
console output: https://syzkaller.appspot.com/x/log.txt?x=17ea0aeae00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7a3b8f5088d4043a
dashboard link: https://syzkaller.appspot.com/bug?extid=0568d05e486eee0a1ba2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15ddeca6e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16df9e41e00000

Reported-by: syzbot+0568d05e486eee0a1ba2 at syzkaller.appspotmail.com
Fixes: 2de50e9674fc ("powerpc/powernv: Remove support for p5ioc2")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection