From: Alan Modra <amodra@gmail.com>
To: Kai Tietz <ktietz70@googlemail.com>
Cc: Binutils <binutils@sourceware.org>, Nick Clifton <nickc@redhat.com>
Subject: Re: [patch bfd]: Prevent possible buffer overflow on pdata-section sorting
Date: Sat, 09 Apr 2011 04:40:00 -0000 [thread overview]
Message-ID: <20110409043456.GG19002@bubble.grove.modra.org> (raw)
In-Reply-To: <BANLkTikcz4aFaUd=Zwm5L-QWG16U1Kb6hQ@mail.gmail.com>
On Thu, Apr 07, 2011 at 04:31:45PM +0200, Kai Tietz wrote:
> 2011/4/7 Alan Modra <amodra@gmail.com>:
> > On Thu, Apr 07, 2011 at 08:15:42AM +0200, Kai Tietz wrote:
> >> Hmm, not sure.
> >
> > Well, I'm 99% sure. :-) Â rawsize on an output section, if non-zero, is
> > just a stale size at bfd_final_link.
>
> So this 1% hits. I changed locally to use here just sec->size and I
> found that pdata section doesn't get sorted proper anymore. (you can
> verify this by objdump -x and it prints warnings about not ascending
> data).
Ah, what I missed seeing is that coff_compute_section_file_positions
is bumping the section size here:
#ifdef COFF_IMAGE_WITH_PE
/* Set the padded size. */
current->size = (current->size + page_size -1) & -page_size;
#endif
Obviously, you do want the size of data before this padding is added,
but it's only a fluke that rawsize happens to be set correctly. (You
get it from the lang_reset_memory_regions call during preliminary
section sizing in ldlang.c:strip_excluded_output_sections.) That
seems a little unreliable to me. I'd be happier if in
coff_compute_section_file_positions you always set rawsize in the loop
that is padding section size (do it before any block of code that
changes section size!). Then just use sec->rawsize in your peXXigen.c
patch. I'll preapprove those changes.
--
Alan Modra
Australia Development Lab, IBM
next prev parent reply other threads:[~2011-04-09 4:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-06 16:50 Kai Tietz
2011-04-06 21:55 ` h.becker
2011-04-07 1:09 ` Alan Modra
2011-04-07 5:55 ` Kai Tietz
2011-04-07 6:15 ` Kai Tietz
2011-04-07 8:52 ` Alan Modra
2011-04-07 14:31 ` Kai Tietz
2011-04-09 4:40 ` Alan Modra [this message]
2011-04-09 9:50 ` Kai Tietz
[not found] ` <20110409131155.GH19002@bubble.grove.modra.org>
[not found] ` <BANLkTikediRDiabar9P0k526O4Pyy_qWSQ@mail.gmail.com>
[not found] ` <20110409140103.GI19002@bubble.grove.modra.org>
2011-04-09 16:07 ` Kai Tietz
2011-04-11 4:08 ` rawsize and output sections Alan Modra
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