[php-src] Issue #13685: Unexpected null pointer in zend_string.h

Issue: https://github.com/php/php-src/issues/13685 Author: YuanchengJiang ### Description The following code: ```php <?php $contents = <<<EOS "cell1","cell2\\","cell3","cell4" "\\\\\\line1 line2\\\\\\" EOS; $file = new SplTempFileObject; $file->fwrite($contents); $file->rewind(); while (($data = $file->fgetcsv(',', '"', ''))) { print_r($data); } $xconnect = $file; $dom = new DOMDocument; $dom->loadXML("<root><x/><x xmlns:a=\"urn:a\" xmlns:b=\"urn:b\"/><x xmlns:b=\"urn:b\" xmlns:a=\"urn:a\"/></root>"); foreach ($dom->getElementsByTagName('x') as $x1) { foreach ($dom->getElementsByTagName('x') as $x2) { echo "Comparing ", $dom->saveXML($x1), " with ", $dom->saveXML($x2), "\n"; var_dump($x1->isEqualNode($x2)); } } $xconnect = $xconnect.$dom; eval($xconnect); ?> ``` See: https://3v4l.org/md1YH Resulted in this output: ``` /WorkSpace/php-src/Zend/zend_string.h:200:24: runtime error: null pointer passed as argument 2, which is declared to never be null /usr/include/string.h:44:28: note: nonnull attribute specified here SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /WorkSpace/php-src/Zend/zend_string.h:200:24 in ``` ### PHP Version PHP 8.4.0-dev ### Operating System ubuntu 22.04