Re: rawtherapee free(): chunk is already free 0x907fb48e800 when not in gdb

Stefan Hagen <sh+openbsd-ports@codevoid.de> wrote:
> Omar Polo wrote (2022-06-29 10:12 CEST):
> > +cc kirby@ (maintainer)
> >
> > Stefan Hagen <sh+openbsd-ports@codevoid.de> wrote:
> > > Abel Abraham Camarillo Ojeda wrote (2022-06-20 08:24 CEST):
> > > > [...]
> > > >
> > > > I now applied the patch correctly, I can no longer reproduce the issue.
> > > >
> > > > upstream seems unresponsive about this, any chance of getting it on ports?
> > >
> > > The one that rips out all setlocale calls? No.
> > >
> > > Here is a better diff, which replaces the setlocale(3) calls with thread
> > > local (and therefore thread-safe) uselocale(3) calls.
> > >
> > > I'm still testing this, because it is not exactly the same as the original.
> > >
> > > If it improves the situation on OpenBSD, I'm not opposed to commit these
> > > patches. Please test and report back.
> >
> > I don't use rawtherapee, and my understanding of the locale api is
> > (voluntarely) scarse, but I'm not sure the patch is right.
> >
> > On OpenBSD there shouldn't be issue, because freelocale (AFAIU) is a
> > no-op, but on other OSes you need to free the locale returned by
> > newlocale or duplocale.
>
> In expanded form we have:
>
> locale_t oldloc = duplocale(LC_GLOBAL_LOCALE);
> locale_t modloc = newlocale(LC_NUMERIC_MASK, "C", oldloc);
> locale_t newloc = uselocale(modloc);
>
> I think we could:
>
> locale_t oldloc = duplocale(LC_GLOBAL_LOCALE);
> locale_t modloc = newlocale(LC_NUMERIC_MASK, "C", oldloc);
> freelocale(oldloc);
> locale_t newloc = uselocale(modloc);
> freelocale(modloc);
^^^^^^
you mean newloc here

> From our uselocale(3) manpage:
>
> The current thread uses newloc until uselocale() is called again
> successfully with a non-null argument in the same thread, and
> passing newloc to freelocale(3) or newlocale(3) before that results
> in undefined behaviour.
>
> I think calling freelocale(newloc) at this point would result in
^^^^^^
and modloc here, right?

modloc is in use after uselocale and freelocale(3) it would cause UB,
while "newloc" is the one used up to that point and _i think_ can be
free'd. No idea what' the default locale for a thread and if that can
be passed to uselocale tho.

> undefined behavior.

yes, as it's in use and it's not a good idea to free a resource that's
being used by something else.

> Best Regards,
> Stefan
>
>
> > See (but not too closely!) the example from the GNU man page for
> > newlocale:
> >
> > https://man.voidlinux.org/newlocale
> >
> > so the patch may be OK for us, but not to fed it to upstream.