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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 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 unsigned int gpiochip_count_reserved_ranges(struct gpio_chip *gc)
> > > +{
> > > + int size;
> > > +
> > > + size = fwnode_property_count_u32(gc->fwnode, "gpio-reserved-ranges");
> >
> > I wonder if a comment why we need even size would not be helpful.
>
> Was it in the original code?
> Anyway, if Bart thinks so as well, I may add it in v2.
>
> > > + if (size > 0 && size % 2 == 0)
> > > + return size;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > static int gpiochip_alloc_valid_mask(struct gpio_chip *gc)
> > > {
> > > - if (!(of_gpio_need_valid_mask(gc) || gc->init_valid_mask))
> > > + if (!(gpiochip_count_reserved_ranges(gc) || gc->init_valid_mask))
> > > return 0;
> > >
> > > gc->valid_mask = gpiochip_allocate_mask(gc);
> > > @@ -457,8 +468,47 @@ static int gpiochip_alloc_valid_mask(struct gpio_chip *gc)
> > > return 0;
> > > }
> > >
> > > +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].

Thanks.

--
Dmitry

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