Re: [PATCH] readelf: Warn zero-sized relocation sections

[Hans-Peter Nilsson <hp@bitrange.com>]

On Mon, 20 Apr 2020, Jan Beulich wrote:

> On 20.04.2020 12:28, Nick Clifton wrote:
> >>>   I am of a mind to allow this patch, given that one of readelf's
> >
> >> While I can see the "diagnose problems" aspect, zero-sized relocation
> >> sections aren't something the ELF standard disallows. So there's no
> >> problem with the ELF files in this case, just a _possible_ problem
> >> with consumers thereof.
> >
> > True - but in this case we are talking about relocation sections, and
> > what possible use is an empty relocation section ?  Its presence is
> > legal sure, but it can also be an indication that the tool that created
> > the binary is not quite doing its job properly.
>
> It is still legitimate for a tool to create _all_ sections it may
> possibly put data into. While now causing headaches, that ppc
> behavior mentioned further down actually demonstrates this.
>
> > I personally like the idea of giving users as much information as possible
> > and allowing them to decide if they want it.  After all it is relatively
> > easy to remove any warning out that is undesired via command line tools.
>
> Is it, even when considering the messages getting translated to
> other languages? What would my pattern be to filter them out
> regardless of language?
>
> Anyway, I merely meant to voice my opinion. You're the maintainer,
> so you've got to judge.

Time to chime in?

I'd like to voice my support for *not* have readelf emit an
empty-section warning by default (whether a relocation section
or not).  Nonetheless it would be very useful as a separate,
non-default, option, say for generally fishy contents.

If it's added anyway, please also add an option to not emit the
warning.

> >>>     readelf: Warning: Section '.rela.dyn': zero-sized relocation section
> >>
> >> Aren't these a good enough indication that zero-sized relocation
> >> sections aren't this unusual, and hence a default-on warning is
> >> going too far?
> >
> > Actually no - these failures have now prompted H.J. and Alan to have a look
> > at the code producing these empty sections and see about fixing them.
>
> Yes, I've seen this. Not emitting these sections is certainly a
> good thing to do, but aiui current behavior is still legitimate
> (and hence I'd call this clean up, not "fixing").
>
> Jan

brgds, H-P