Re: [Minios-devel] [UNIKRAFT RFC PATCH] plat/common:Add helper to simplify accessing fdt for arm

[Julien Grall <julien.grall@xxxxxxx>]

On 11/15/18 6:09 AM, Jianyong Wu (Arm Technology China) wrote:
> Hi,
Hi,


> > > > +
> > > > +       UK_ASSERT(device != -1);
> > > > +        naddr = fdt_address_cells(dtb, device);
> > > > +        UK_ASSERT(naddr < FDT_MAX_NCELLS);
> > > > +
> > > > +        *nsize = fdt_size_cells(dtb, device);
> > > > +        UK_ASSERT(*nsize < FDT_MAX_NCELLS);
> > > > +
> > > > +        *regs = fdt_getprop(dtb, device, "reg", &prop_len);
> > > > +        prop_min_len = (int)sizeof(fdt32_t) * (naddr + *nsize);
> > > > +        UK_ASSERT(*regs != NULL && prop_len >= prop_min_len);
> > > This assert is not very useful for "regs" property describing more
> > > than
> > > 1 regions. I think it would make sense to move the check in the
> > > uk_dtb_read_term to check if the region requested by the caller is correct.
> > Ok, I will check reg in uk_dtb_read_term.
> But, how to check reg in uk_dtb_read_term? I have an idea that check *(reg + 
> index*(naddr+nsize) *4)
> Does that make sence?
You want to make sure you are not going to read past the size of the 
property. So ((index + 1) * (naddr + nsize) * 4) < size should be fine.
Cheers,

--
Julien Grall

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