Re: [PATCH] loop: add recursion validation to LOOP_CHANGE_FD

["Theodore Y. Ts'o" <tytso@mit.edu>]

On Mon, May 07, 2018 at 08:16:58PM +0900, Tetsuo Handa wrote:
> Oh, your message did not arrive at news.gmane.org and I didn't notice that you
> already wrote this patch. But please update yours or review mine shown below.
> 
> > @@ -673,14 +703,13 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
> >  	if (!file)
> >  		goto out;
> >  
> > +	error = loop_validate_file(file, bdev);
> > +	if (error)
> > +		goto out_putf;
> > +
> >  	inode = file->f_mapping->host;
> >  	old_file = lo->lo_backing_file;
> >  
> > -	error = -EINVAL;
> > -
> > -	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
> > -		goto out_putf;
> > -
> >  	/* size of the new backing store needs to be the same */
> >  	if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
> >  		goto out_putf;
> 
> error == 0 upon "goto out_putf" is wrong.

I don't understand your concern; where are we going to out_putf when
error == 0?

The relevant code that was added is:

	error = loop_validate_file(file, bdev);
	if (error)
		goto out_putf;


						- Ted