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Fix segfault when DOMParentNode::prepend() is called when the child disappears #11906

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Fix segfault when DOMParentNode::prepend() is called when the child disappears #11906

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ecd0a68
Fix segfault when DOMParentNode::prepend() is called when the child d…
nielsdos Aug 7, 2023
8f8521b
Move dom_pre_insert up in the file
nielsdos Aug 7, 2023
a8e1e77
Use dom_pre_insert and be done with it
nielsdos Aug 7, 2023
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63 changes: 30 additions & 33 deletions ext/dom/parentnode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -280,6 +280,33 @@ static zend_result dom_sanity_check_node_list_for_insertion(php_libxml_ref_obj *
return SUCCESS;
}

static void dom_pre_insert(xmlNodePtr insertion_point, xmlNodePtr parentNode, xmlNodePtr newchild, xmlNodePtr fragment)
{
if (!insertion_point) {
/* Place it as last node */
if (parentNode->children) {
/* There are children */
newchild->prev = parentNode->last;
parentNode->last->next = newchild;
} else {
/* No children, because they moved out when they became a fragment */
parentNode->children = newchild;
}
parentNode->last = fragment->last;
} else {
/* Insert fragment before insertion_point */
fragment->last->next = insertion_point;
if (insertion_point->prev) {
insertion_point->prev->next = newchild;
newchild->prev = insertion_point->prev;
}
insertion_point->prev = fragment->last;
if (parentNode->children == insertion_point) {
parentNode->children = newchild;
}
}
}

void dom_parent_node_append(dom_object *context, zval *nodes, int nodesc)
{
xmlNode *parentNode = dom_object_get_node(context);
Expand Down Expand Up @@ -331,21 +358,18 @@ void dom_parent_node_prepend(dom_object *context, zval *nodes, int nodesc)
return;
}

xmlNodePtr newchild, nextsib;
xmlNode *fragment = dom_zvals_to_fragment(context->document, parentNode, nodes, nodesc);

if (fragment == NULL) {
return;
}

newchild = fragment->children;
nextsib = parentNode->children;
xmlNode *newchild = fragment->children;

if (newchild) {
xmlNodePtr last = fragment->last;
parentNode->children = newchild;
fragment->last->next = nextsib;
nextsib->prev = last;

dom_pre_insert(parentNode->children, parentNode, newchild, fragment);

dom_fragment_assign_parent_node(parentNode, fragment);

Expand All @@ -355,33 +379,6 @@ void dom_parent_node_prepend(dom_object *context, zval *nodes, int nodesc)
xmlFree(fragment);
}

static void dom_pre_insert(xmlNodePtr insertion_point, xmlNodePtr parentNode, xmlNodePtr newchild, xmlNodePtr fragment)
{
if (!insertion_point) {
/* Place it as last node */
if (parentNode->children) {
/* There are children */
newchild->prev = parentNode->last;
parentNode->last->next = newchild;
} else {
/* No children, because they moved out when they became a fragment */
parentNode->children = newchild;
}
parentNode->last = fragment->last;
} else {
/* Insert fragment before insertion_point */
fragment->last->next = insertion_point;
if (insertion_point->prev) {
insertion_point->prev->next = newchild;
newchild->prev = insertion_point->prev;
}
insertion_point->prev = fragment->last;
if (parentNode->children == insertion_point) {
parentNode->children = newchild;
}
}
}

void dom_parent_node_after(dom_object *context, zval *nodes, int nodesc)
{
/* Spec link: https://dom.spec.whatwg.org/#dom-childnode-after */
Expand Down
37 changes: 37 additions & 0 deletions ext/dom/tests/gh11906.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,37 @@
--TEST--
GH-11906 (prepend without children after creating fragment results in segfault)
--EXTENSIONS--
dom
--FILE--
<?php
$doc = new DOMDocument;
$doc->loadXML(<<<XML
<?xml version="1.0"?>
<container>
<child/>
</container>
XML);

$container = $doc->documentElement;
$child = $container->firstElementChild;

$test = $doc->createElement('foo');
$test->append($child);
echo $doc->saveXML();
echo $doc->saveXML($test), "\n";
$test->prepend($child);
echo $doc->saveXML();
echo $doc->saveXML($test), "\n";
$test->append($child);
Comment on lines +18 to +25
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I can't make out where the output of one echo ends and where another echo starts.

Maybe add some ``echo "----------\n";` to make it more obvious?

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I've done so in the merge. If you're interested: d19e4da#diff-8386e35f446a7f90b1425135e71fddb65f86c1c115255c0a454878881e7beeb2

?>
--EXPECT--
<?xml version="1.0"?>
<container>

</container>
<foo><child/></foo>
<?xml version="1.0"?>
<container>

</container>
<foo><child/></foo>