Re: pgsql: Implementation of subscripting for jsonb

On Mon, Feb 1, 2021 at 3:41 PM Alexander Korotkov <aekorotkov@gmail.com> wrote:
> On Mon, Feb 1, 2021 at 10:06 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Heikki Linnakangas <hlinnaka@iki.fi> writes:
> > > On 31/01/2021 22:54, Alexander Korotkov wrote:
> > >> Implementation of subscripting for jsonb
> >
> > > The Itanium and sparc64 buildfarm members didn't like this, and are
> > > crashing at "select ('123'::jsonb)['a'];". Unaligned memory access, perhaps?
> >
> > I think I just identified the cause.
>
> Thanks again for fixing this.
>
> BTW, I managed to reproduce the issue by compiling with CFLAGS="-O0
> -fsanitize=alignment -fsanitize-trap=alignment" and the patch
> attached.
>
> I can propose the following to catch such issues earlier.  We could
> finish (wrap attribute with macro and apply it to other places with
> misalignment access if any) and apply the attached patch and make
> commitfest.cputube.org check patches with CFLAGS="-O0
> -fsanitize=alignment -fsanitize-trap=alignment".  What do you think?

The revised patch is attached.  The attribute is wrapped into
pg_attribute_no_sanitize_alignment() macro.  I've checked it works for
me with gcc-10 and clang-11.

------
Regards,
Alexander Korotkov