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ext/dom: Fix use-after-free in getElementById() after removing an ID attribute #25351

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ext/dom: Fix use-after-free in getElementById() after removing an ID attribute #25351

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2 changes: 2 additions & 0 deletions NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,8 @@ PHP NEWS
- DOM:
. Fixed bug GH-25268 (NULL php_libxml_ref_obj dereference in
dom_objects_store_clone_obj when cloning Dom\Notation). (David Carlier)
. Fixed use-after-free in getElementById() after a removed ID attribute is
freed. (Ilia Alshanetsky)

- MBString:
. Fixed stack overflow in mb_check_encoding() and mb_convert_encoding() with
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56 changes: 56 additions & 0 deletions ext/dom/tests/getElementById_removed_id_attribute.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,56 @@
--TEST--
getElementById() after a removed ID attribute is freed
--EXTENSIONS--
dom
--FILE--
<?php

$doc = new DOMDocument();
$doc->loadXML('<root><a xml:id="x"/><b xml:id="y"/></root>');
$a = $doc->documentElement->firstChild;
$attr = $a->getAttributeNode('xml:id');
$a->removeAttributeNode($attr);
unset($attr);
echo "removed id: ";
var_dump($doc->getElementById('x'));
echo "remaining id: ", $doc->getElementById('y')->nodeName, "\n";

$doc = new DOMDocument();
$doc->loadXML('<!DOCTYPE root [<!ATTLIST e id ID #IMPLIED>]><root><e id="x"/><e id="y"/></root>');
$e = $doc->documentElement->firstChild;
$attr = $e->getAttributeNode('id');
$e->removeAttributeNode($attr);
unset($attr);
echo "removed DTD id: ";
var_dump($doc->getElementById('x'));
echo "remaining DTD id: ", $doc->getElementById('y')->nodeName, "\n";

$doc = Dom\XMLDocument::createFromString('<root><a xml:id="x"/><b xml:id="y"/></root>');
$a = $doc->documentElement->firstChild;
$attr = $a->getAttributeNode('xml:id');
$a->removeAttributeNode($attr);
unset($attr);
echo "removed Dom\\XMLDocument id: ";
var_dump($doc->getElementById('x'));
echo "remaining Dom\\XMLDocument id: ", $doc->getElementById('y')->nodeName, "\n";

$doc = new DOMDocument();
$doc->loadXML('<root><a xml:id="x"/><b xml:id="y"/></root>');
$a = $doc->documentElement->firstChild;
$attr = $a->getAttributeNode('xml:id');
$a->removeAttribute('xml:id');
unset($attr);
echo "removeAttribute() id: ";
var_dump($doc->getElementById('x'));
echo "remaining removeAttribute() id: ", $doc->getElementById('y')->nodeName, "\n";

?>
--EXPECT--
removed id: NULL
remaining id: b
removed DTD id: NULL
remaining DTD id: e
removed Dom\XMLDocument id: NULL
remaining Dom\XMLDocument id: b
removeAttribute() id: NULL
remaining removeAttribute() id: b
3 changes: 3 additions & 0 deletions ext/libxml/libxml.c
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Expand Up @@ -1480,6 +1480,9 @@ PHP_LIBXML_API void php_libxml_node_free_resource(xmlNodePtr node)
break;
default:
if (node->parent == NULL || node->type == XML_NAMESPACE_DECL) {
if (node->type == XML_ATTRIBUTE_NODE && node->doc != NULL && ((xmlAttrPtr) node)->atype == XML_ATTRIBUTE_ID) {
xmlRemoveID(node->doc, (xmlAttrPtr) node);
}
php_libxml_node_free_list((xmlNodePtr) node->children);
if (node->type == XML_ELEMENT_NODE) {
php_libxml_node_free_list((xmlNodePtr) node->properties);
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