Re: [PATCH v2 2/2] software node: Fix software_node_get_reference_args() with index -1

[Andy Shevchenko]

On Sat, Jun 27, 2026 at 07:50:12AM +0800, Zijun Hu wrote:
> On 6/18/2026 11:20 PM, Alban Bedel wrote:
> > The bounds check for the index passed to
> > software_node_get_reference_args() was failing when passed UINT_MAX,
> > this in turn would lead to an out of bound access in the property
> > array. Fix the bound check to also cover the UINT_MAX case.
> > 
> > Fixes: 31e4e12e0e960 ("software node: Correct a OOB check in software_node_get_reference_args()")
> 
> i think the fix tag may not be right.
> 
> for original express before the fix tag: if (index * sizeof(*ref) > prop->length)
> 
> for UINT_MAX, multiplication overflow?

I agree that Fixes tag may be not the best chosen.

...

> > software_node_get_reference_args(const struct fwnode_handle *fwnode,

> >  	if (prop->is_inline)
> >  		return -EINVAL;
> >  
> > -	if ((index + 1) * sizeof(*ref) > prop->length)
> > +	if (index >= prop->length / sizeof(*ref))
> >  		return -ENOENT;
> >  
> 
> who will use UINT_MAX ?
> 
> This function is a interface function.  the best fix should check
> input parameter @index and return -EINVAL if it is not expected?

And how do you know which index is allowed without doing that division?
Basically this patch does what you asked for: check input parameter for
the allowed range (which is dynamic, depending on the property length and
size of the reference structure.


-- 
With Best Regards,
Andy Shevchenko