[PATCH v2] tools: ensure zeroed padding in external FIT images

[Simon Glass]

Hi Roman,

On Mon, 28 Aug 2023 at 02:00, Roman Azarenko <roman.azarenko at iopsys.eu> wrote:
>
> On Fri, 2023-08-25 at 12:06 -0600, Simon Glass wrote:
> > > @@ -564,9 +564,13 @@ static int fit_extract_data(struct
> > > image_tool_params *params, const char *fname)
> > >          /* Pack the FDT and place the data after it */
> > >          fdt_pack(fdt);
> > >
> > > -       new_size = fdt_totalsize(fdt);
> > > -       new_size = ALIGN(new_size, align_size);
> > > +       unpadded_size = fdt_totalsize(fdt);
> > > +       new_size = ALIGN(unpadded_size, align_size);
> > >          fdt_set_totalsize(fdt, new_size);
> >
> > I didn't know that was allowed...I thought it needed fdt_open_into() ?
>
> The introduction of fdt_set_totalsize() comes from commit ebfe611be91e
> ("mkimage: fit_image: Add option to make fit header align"). The commit
> message doesn't describe the choice of this function vs fdt_open_into().
>
> Personally I'm unable to definitively comment on it. I can only blindly
> guess, that because we're only changing the total length of the fdt
> struct, and keeping all other fields the same, we don't need to allocate
> a new fdt struct with a different size.

I am not sure if it would cause problems. I do understand that you
didn't write the code. You could copy the people who did (and those
that reviewed it) for their input.

But I think it should change to call fdt_open_into()...if you look at
that function it does extra things. Unfortunately, the function has no
comment in libfdt.h.

Could you add another patch before or after this one?

Regards,
Simon