Re: [PATCH 1/6] property: add fwnode_property_read_string_index()

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Fri, Mar 18, 2022 at 05:49:12PM +0100, Clément Léger wrote:
> Le Fri, 18 Mar 2022 18:26:00 +0200,
> Andy Shevchenko <andriy.shevchenko@linux.intel.com> a écrit :
> > On Fri, Mar 18, 2022 at 05:00:47PM +0100, Clément Léger wrote:
> > > Add fwnode_property_read_string_index() function which allows to
> > > retrieve a string from an array by its index. This function is the
> > > equivalent of of_property_read_string_index() but for fwnode support.  

...

> > > +	values = kcalloc(nval, sizeof(*values), GFP_KERNEL);
> > > +	if (!values)
> > > +		return -ENOMEM;
> > > +
> > > +	ret = fwnode_property_read_string_array(fwnode, propname, values, nval);
> > > +	if (ret < 0)
> > > +		goto out;
> > > +
> > > +	*string = values[index];
> > > +out:
> > > +	kfree(values);  
> > 
> > Here is UAF (use after free). How is it supposed to work?
> 
> values is an array of pointers. I'm only retrieving a pointer out of
> it.

I see, thanks for pointing out.

Nevertheless, I don't like the idea of allocating memory in this case.
Can we rather add a new callback that will provide us the necessary
property directly?

-- 
With Best Regards,
Andy Shevchenko