Re: [PATCH v3] readelf: Save and dump the original section header values

On Thu, Jul 9, 2026 at 2:06 PM Jan Beulich <[email protected]> wrote:
>
> On 04.07.2026 13:06, H.J. Lu wrote:
> > On Sat, Jul 4, 2026 at 11:01 AM H.J. Lu <[email protected]> wrote:
> >> On Sat, Jul 4, 2026 at 8:39 AM H.J. Lu <[email protected]> wrote:
> >>> On Sat, Jul 4, 2026 at 7:49 AM Alan Modra <[email protected]> wrote:
> >>>>
> >>>> On Fri, Jul 03, 2026 at 10:30:14PM +0800, H.J. Lu wrote:
> >>>>> validate_section_info clears the garbage values in the section header
> >>>>> to avoid crash later.  Save and dump the original section header values
> >>>>> to make the garbage values in the section header visible when dumping
> >>>>> section headers.
> >>>>
> >>>> I think this would be better done the other way around.  ie. have a
> >>>> Elf_Internal_Shdr **sane_section_headers that is initialised to point
> >>>> at entries in section_headers, with sane_section_headers[i] allocated
> >>>> as necessary when needing to correct a bogus header.
> >>>>
> >>>
> >>> I have thought about something similar and decided against it
> >>> since filedata->section_headers is used in many places.   However,
> >>> I can change filedata->orig_section_headers to on demand.
>
> I find this a plausible argument, so ...
>
> >> Changes in v2:
> >>
> >> 1.  filedata->orig_section_headers is changed to on demand.
> >
> > Changes in v3:
> >
> > 1.  Clear filedata->orig_section_headers first.
>
> ... the patch is okay unless you get an objection from Alan within another

Will do.

> day or two. Just one thing though: calloc() + memset(, 0,) is redundant.
> Please drop those memset()s.

It is cmalloc, not calloc:

  filedata->orig_section_headers = (Elf_Internal_Shdr **)
    cmalloc (num, sizeof (Elf_Internal_Shdr *));

cmalloc doesn't clear memory.  memset is needed.

> Jan

-- 
H.J.