On Mon, Mar 21, 2022 at 08:49:21AM +0100, Clément Léger wrote:

Le Fri, 18 Mar 2022 20:09:37 +0200,
Andy Shevchenko [off-list ref] a écrit :

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On Fri, Mar 18, 2022 at 05:49:12PM +0100, Clément Léger wrote:

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Le Fri, 18 Mar 2022 18:26:00 +0200,
Andy Shevchenko [off-list ref] a écrit :  

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On Fri, Mar 18, 2022 at 05:00:47PM +0100, Clément Léger wrote:  

...

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+	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?

IMHO, it would indeed be better. However,
fwnode_property_match_string() also allocates memory to do the same
kind of operation. Would you also like a callback for this one ?

But matching string will need all of them to cover all possible cases.
So, it doesn't rely on the certain index and needs allocation anyway.

-- 
With Best Regards,
Andy Shevchenko