Re: KASAN: use-after-free Read in blkdev_get

[syzbot]

syzbot has bisected this bug to:

commit 77ef8f5177599efd0cedeb52c1950c1bd73fa5e3
Author: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Date:   Mon Jan 25 20:05:34 2016 +0000

    tile kgdb: fix bug in copy to gdb regs, and optimize memset

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1131bc0ee00000
start commit:   f5b7769e Revert "debugfs: inode: debugfs_create_dir uses m..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1331bc0ee00000
console output: https://syzkaller.appspot.com/x/log.txt?x=1531bc0ee00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=709f8187af941e84
dashboard link: https://syzkaller.appspot.com/bug?extid=eaeb616d85c9a0afec7d
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=177f898f800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=147eb85f800000

Reported-by: syzbot+eaeb616d85c9a0afec7d@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 77ef8f517759 ("tile kgdb: fix bug in copy to gdb regs, and optimize  
memset")

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