Re: WARNING: refcount bug in chrdev_open

[syzbot]

syzbot suspects this bug was fixed by commit:

commit 68faa679b8be1a74e6663c21c3a9d25d32f1c079
Author: Will Deacon <will@xxxxxxxxxx>
Date:   Thu Dec 19 12:02:03 2019 +0000

    chardev: Avoid potential use-after-free in 'chrdev_open()'

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14412659e00000
start commit:   81b6b964 Merge branch 'master' of git://git.kernel.org/pub..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=d98e4bd76baeb821
dashboard link: https://syzkaller.appspot.com/bug?extid=1c85a21f1c6bc88eb388
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=147ad0a6e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15483312e00000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: chardev: Avoid potential use-after-free in 'chrdev_open()'

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