Re: bytea(uuid) missing proleakproof?

Hi,

On Sun, Jun 21, 2026 at 9:00 PM Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>
> Hi,
>
> While testing "[ba21f5bf8] Allow explicit casting between bytea and uuid", I noticed that the new proc bytea(uuid) is not marked as proleakproof, while the other functions in the group, bytea(int2), bytea(int4), and bytea(int8), are all marked as proleakproof.
>
> Looking into the backend function uuid_bytea(), it just returns uuid_send(fcinfo). For a valid uuid datum, uuid_send() only copies the UUID value into a bytea result, so I don't see an input-dependent error path or other reason not to mark bytea(uuid) as proleakproof.
>
> This matters for security barrier planning, because a qual using uuid::bytea is otherwise treated as leaky and cannot be pushed down. Attached is a tiny patch to fix that.
>
> I didn't mark uuid_send() itself as proleakproof because none of send/receive functions are marked as proleakproof in pg_proc.dat.

Thank you for the report.

I agree that we should mark bytea(uuid) (i.e., converting uuid ->
bytea) as leakproof but not the opposite direction.

The patch is simple and looks good to me. I'll push the patch, barring
any objections.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com