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Fix uaf in SplDoublyLinkedList::offsetSet() #16466

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Fix uaf in SplDoublyLinkedList::offsetSet() #16466

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29 changes: 29 additions & 0 deletions Zend/tests/gh16464.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
--TEST--
GH-16464: Use-after-free in SplDoublyLinkedList::offsetSet() when modifying list in destructor of overwritten object
--FILE--
<?php

class C {
public $a;

function __destruct() {
global $list;
var_dump($list->pop());
}
}

$list = new SplDoublyLinkedList;
$list->add(0, new C);
$list[0] = 42;
var_dump($list);

?>
--EXPECTF--
int(42)
object(SplDoublyLinkedList)#%d (2) {
["flags":"SplDoublyLinkedList":private]=>
int(0)
["dllist":"SplDoublyLinkedList":private]=>
array(0) {
}
}
4 changes: 3 additions & 1 deletion ext/spl/spl_dllist.c
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Original file line number Diff line number Diff line change
Expand Up @@ -737,8 +737,10 @@ PHP_METHOD(SplDoublyLinkedList, offsetSet)
if (element != NULL) {
/* the element is replaced, delref the old one as in
* SplDoublyLinkedList::pop() */
zval_ptr_dtor(&element->data);
zval garbage;
ZVAL_COPY_VALUE(&garbage, &element->data);
ZVAL_COPY(&element->data, value);
zval_ptr_dtor(&garbage);
} else {
zval_ptr_dtor(value);
zend_argument_error(spl_ce_OutOfRangeException, 1, "is an invalid offset");
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