Re: [REVIEW 3-6] Fix for Calc crasher

Hi JB,

On Fri, Nov 2, 2012 at 8:24 AM, Jean-Baptiste Faure <jbf.faure@sud-ouest.org
> wrote:

> Le 02/11/2012 01:42, Kohei Yoshida a écrit :
> > Hi there,
> >
> > I'd like the attached patchpushed to the 3-6 branch.
> >
> > Without this patch, doing the following
> >
> > 1. Create a new Calc document.
> > 2. Type some stuff into Cell D5.
> > 3. Move the cursor to Cell C5.
> > 4. Ctrl-+ to launch the Insert Cells dialog. Select Shift cell right
> > and hit OK.
> > 5. Ctrl-Z to undo.
> >
> > Would crash Calc right away.
>
> Hi Kohei,
>
> I do not reproduce the crash with LO 3.6.3.2 under Ubuntu 12.04 x86_64
>
> But I reproduce the crash on LO 3.6.4.0+ if I revert your commit.

So, this is a memory corruption, where a stale pointer would point to a
non-existent cell instance. That means that sometimes you may get lucky and
don't see the crash if the memory space the pointer is pointing to contains
the "right" value by chance.  I think with the version of 3.6.3.2 that you
used you just got "lucky".  That wrong code had been there way before the
initial 3.6.0 release; it's not something that was introduced between the
3.6.x releases.

But even if you couldn't reproduce this very crasher, it would have caused
other, hard-to-reproduce crasher somewhere else.

Anyway, thanks for your test.

Kohei