[PATCH] makedumpfile: readpage_elf: handle 0-pages not stored in the ELF file

[Ivan Delalande]

Hi,

On Tue, Feb 09, 2016 at 09:31:50AM +0100, Petr Tesarik wrote:
> On Tue, 2 Feb 2016 08:00:44 +0100 Ivan Delalande <colona at arista.com> wrote:
> > On Tue, Feb 02, 2016 at 06:48:17AM +0000, Atsushi Kumagai wrote:
> > > >Anyway, are you going to take the patch by Ivan, or my patch (after I
> > > >remove exclude_nodata_pages)?
> > > 
> > > Ivan's patch is necessary to follow the ELF specification, but also
> > > your patch (with exclude_nodata_pages) should be merged.
> > > The two patches have different approach to expand struct pt_load_segment,
> > > hence could you manage both work ?
> > > 
> > > Ivan, your v2 patch has no problems, but could I leave this work to Petr
> > > since the two patches touch the same area ?
> > 
> > Sure, this sounds reasonable.
> 
> just a short status update. I haven't forgotten this patch, but I've
> had some troubles reproducing the issue. To make sure I'm not on the
> wrong track, what happened when you tried to dump dmesg on the affected
> dump file without the patch?
> 
> For me, I crafted a dump file which causes a segfault. Did makedumpfile
> also terminate on SIGSEGV? Did it report an error? Or did it just
> produce wrong output?

Yeah, just a segfault, without any other message or output. It was
coming from readpage_elf, at the call to memset in the `if (!offset1)`
block, as it thinks it is handling one of this weird overlapping
segments from ia64 and computes bad offsets.

Thank you,
-- 
Ivan "Colona" Delalande
Arista Networks