bug#51688: ELC+ELN international/emoji.elc crashes

[Martin Liška]

On 11/24/21 16:14, Andrea Corallo wrote:
> Eli Zaretskii <eliz@gnu.org> writes:
>
> > > From: Andreas Schwab <schwab@linux-m68k.org>
> > > Cc: rpluim@gmail.com,  akrl@sdf.org,  51688@debbugs.gnu.org
> > > Date: Wed, 24 Nov 2021 14:06:04 +0100
> > >
> > > On Nov 24 2021, Eli Zaretskii wrote:
> > >
> > > > Do you happen to know which libgccjit versions are affected by the
> > > > bug?  We could tell people to avoid them.
> > >
> > > Most likely all of them.
> >
> > Too bad.
> >
> > Andrea, can anything be done to work around this somehow (except to
> > upgrade to a later GCC)?  Or is there nothing we can do except keep
> > fingers crossed?
>
> I don't think there's much we can do to work around this on Emacs side
> (Martin please correct me if I'm wrong).

No, it's UBSAN in libgccjit library. Unfortunately, the issue is there
for quite a long time and it was exposed by a bad luck where an used
memory was reused (and not initialized) in libgccjit.

Martin

> > > > Or did this bug exist since day one?  (But if it's an old bug, why
> > > > doesn't everyone see these crashes?)
> > >
> > > That's the effect of undefined behaviour.
> >
> > You mean, undefined behavior in libgccjit's own code, right?  Or in
> > our code?
>
> In libgccjit's own code.
>
> BR
>
>    Andrea