Re: BUG #15632: Correctly escaped strings are mishandled in function

On Mon, Feb 11, 2019 at 11:22 AM Kaleb Akalework
<kaleb.akalework@asg.com> wrote:

>     v_sql :=          ' WITH upd AS ( ';
>     v_sql := v_sql || ' UPDATE ' || v_tpc_db_table || ' ';
>     v_sql := v_sql || ' SET topic_value = ' || v_replace_str || ' ';
>     v_sql := v_sql || ' WHERE topic_value = ''' || p_old_value || ''' ';
>     v_sql := v_sql || ' RETURNING 1 ) ';
>     v_sql := v_sql || ' SELECT COUNT(*) FROM upd ';

PostgreSQL provides two features to avoid writing SQL-injection prone
code like this.  Use one of them.

quote_literal() and related functions

The format() function and its %L and related specifiers.

You can also place "$n" placeholders into the dynamic command as pass
literals in via EXECUTE USING.

Or some combination of the above.

This is all nicely covered in the documentation for pl/pgsql regarding
executing dynamic commands.

https://www.postgresql.org/docs/11/plpgsql-statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN

David J.