Date: Mon, 6 Jan 2025 11:04:28 -0800
From: Noah Misch <noah@leadboat.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Ronan Dunklau <ronan.dunklau@aiven.io>, Tom Lane <tgl@sss.pgh.pa.us>,
	pgsql-hackers@lists.postgresql.org,
	Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Subject: Re: Converting contrib SQL functions to new style
Message-ID: <20250106190428.ec.nmisch@google.com>
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On Tue, Nov 12, 2024 at 05:30:30PM +0900, Michael Paquier wrote:
> 0004 for pg_freespace is fine regarding that for example as we have
> calls of pg_freespace(regclass) in its sql/.  I've applied it to begin
> with something.

That commit (3f323eb) contains a generate_series(int, bigint) call.  Following
https://www.postgresql.org/docs/current/ddl-schemas.html#DDL-SCHEMAS-PATTERNS
is enough in v17, but it wouldn't be enough after that commit.  An attacker
can achieve persistent capture of the inexact call:

set search_path = pg_catalog;
create or replace function public.generate_series(int, bigint) returns bigint
  language plpgsql as $$
BEGIN
	RAISE NOTICE 'owned';
	RETURN 0;
END
$$;
create extension pg_freespacemap schema public;
select public.pg_freespace(0);
\sf public.pg_freespace(regclass)

Per postgr.es/m/3489827.1618411777@sss.pgh.pa.us and
postgr.es/m/1471865.1734212070@sss.pgh.pa.us one requirement for migrating to
SQL-standard function bodies is removing these inexact-match function and
operator calls.  Here, one could either write pg_catalog.generate_series or
make the argument types match exactly.