pgsql: potential use after free when using persistent connections

[MagicalTux]

Description

ext/pgsql sets a notice processor callback on connection in ext/pgsql/pgsql.c on or around line 820.

When using persistent connections with pg_pconnect, if a notice is received while a connection isn't in use (ie. in the pool), the callback libpg was provided with (_php_pgsql_notice_handler) will attempt to access its parameter link even through it is not valid anymore as it was scoped to the request.

Upon clearing (likely in _rollback_transactions) the notice processor should be set to a no-op handler.

(note: passing NULL to PQsetNoticeProcessor will not do anything except return the previous callback).

PHP Version

PHP 8.4.11 (cli) (built: Aug 12 2025 02:25:03) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.4.11, Copyright (c) Zend Technologies
    with Zend OPcache v8.4.11, Copyright (c), by Zend Technologies

Operating System

Linux

[devnexen]

Hi @MagicalTux thanks for your analysis, would you mind making a PR ? If yes, PHP-8.3 branch should be targeted. Cheers