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SubjectRe: [PATCH v1 2/2] gpiolib: of: Integrate of_gpiochip_init_valid_mask() into gpiochip_init_valid_mask()
On Mon, Nov 07, 2022 at 01:40:53PM -0800, Dmitry Torokhov wrote:
> On Mon, Nov 07, 2022 at 11:09:19PM +0200, Andy Shevchenko wrote:
> > On Mon, Nov 07, 2022 at 10:20:37AM -0800, Dmitry Torokhov wrote:
> > > On Mon, Nov 07, 2022 at 06:10:27PM +0200, Andy Shevchenko wrote:

...

> > > > +static int gpiochip_apply_reserved_ranges(struct gpio_chip *gc, unsigned int sz)
> > > > +{
> > > > + u32 *ranges;
> > > > + int ret;
> > > > +
> > > > + ranges = kmalloc_array(sz, sizeof(*ranges), GFP_KERNEL);
> > > > + if (!ranges)
> > > > + return -ENOMEM;
> > > > +
> > > > + ret = fwnode_property_read_u32_array(gc->fwnode, "gpio-reserved-ranges", ranges, sz);
> > > > + if (ret) {
> > > > + kfree(ranges);
> > > > + return ret;
> > > > + }
> > > > +
> > > > + while (sz) {
> > > > + u32 count = ranges[--sz];
> > > > + u32 start = ranges[--sz];
> > >
> > > I know we checked sz validity, but I wonder if re-checking it in this
> > > function would not insulate us from errors creeping in after some other
> > > code refactoring.
> >
> > I'm not sure I understand what you meant. The fwnode_property_read_u32_array()
> > will fail if the given sz is too big for the real data, so while (sz) would
> > never even go on the invalid data.
>
> I am more worried about sz being odd and the loop ending up trying to
> dereference ranges[-1].

I see. What if we take amount of ranges as the parameter and convert to size by
multiplying by 2?

--
With Best Regards,
Andy Shevchenko


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