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Fix use-after-free during lazy object initialization #22401

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Fix use-after-free during lazy object initialization #22401

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39 changes: 39 additions & 0 deletions Zend/tests/lazy_objects/gh22399.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
--TEST--
GH-22399 (Lazy object revert init with object destructor can lead to double free)
--FILE--
<?php

class A {
public $b;
}

class B {
public function __construct(public $a) {}
public function __destruct() {
unset($this->a->b);
}
}

$reflector = new ReflectionClass(A::class);

$a = $reflector->newLazyGhost(function (A $a) {
$a->b = new B($a);
throw new Exception('initializer exception');
});

try {
$a->any;
} catch (Exception $e) {
printf("%s\n", $e->getMessage());
}

var_dump($a);
printf("Is lazy: %d\n", $reflector->isUninitializedLazyObject($a));
echo "done\n";
?>
--EXPECTF--
initializer exception
lazy ghost object(A)#%d (0) {
}
Is lazy: 1
done
40 changes: 40 additions & 0 deletions Zend/tests/lazy_objects/gh22399_dynamic_props.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
--TEST--
GH-22399 (Lazy object revert init double free, dynamic property variant)
--FILE--
<?php

#[AllowDynamicProperties]
class A {
public $trigger;
}

class B {
public function __construct(public $a) {}
public function __destruct() {
unset($this->a->dyn);
}
}

$reflector = new ReflectionClass(A::class);

$a = $reflector->newLazyGhost(function (A $a) {
$a->dyn = new B($a);
throw new Exception('initializer exception');
});

try {
$a->trigger;
} catch (Exception $e) {
printf("%s\n", $e->getMessage());
}

var_dump($a);
printf("Is lazy: %d\n", $reflector->isUninitializedLazyObject($a));
echo "done\n";
?>
--EXPECTF--
initializer exception
lazy ghost object(A)#%d (0) {
}
Is lazy: 1
done
40 changes: 40 additions & 0 deletions Zend/tests/lazy_objects/gh22399_proxy.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
--TEST--
GH-22399 (Lazy object double free, proxy cleanup variant)
--FILE--
<?php

#[AllowDynamicProperties]
class A {
public $trigger;
public $b;
}

class B {
public function __construct(public $proxy) {}
public function __destruct() {
unset($this->proxy->b);
}
}

class C {
public function __construct(public $proxy) {}
public function __destruct() {
unset($this->proxy->dyn);
}
}

$reflector = new ReflectionClass(A::class);

$a = $reflector->newLazyProxy(function (A $a) {
$a->b = new B($a);
$a->dyn = new C($a);
return new A();
});

$a->trigger;
var_dump($reflector->isUninitializedLazyObject($a));
echo "done\n";
?>
--EXPECT--
bool(false)
done
34 changes: 29 additions & 5 deletions Zend/zend_lazy_objects.c
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Original file line number Diff line number Diff line change
Expand Up @@ -417,7 +417,18 @@ static void zend_lazy_object_revert_init(zend_object *obj, zval *properties_tabl
}

zval *p = &properties_table[OBJ_PROP_TO_NUM(prop_info->offset)];
zend_object_dtor_property(obj, p);
if (Z_REFCOUNTED_P(p)) {
if (UNEXPECTED(Z_ISREF_P(p)) &&
(ZEND_DEBUG || ZEND_REF_HAS_TYPE_SOURCES(Z_REF_P(p)))) {
if (ZEND_TYPE_IS_SET(prop_info->type)) {
ZEND_REF_DEL_TYPE_SOURCE(Z_REF_P(p), prop_info);
}
}
zval garbage;
ZVAL_COPY_VALUE(&garbage, p);
ZVAL_UNDEF(p);
i_zval_ptr_dtor(&garbage);
}
ZVAL_COPY_VALUE_PROP(p, &properties_table_snapshot[OBJ_PROP_TO_NUM(prop_info->offset)]);

if (Z_ISREF_P(p) && ZEND_TYPE_IS_SET(prop_info->type)) {
Expand All @@ -430,15 +441,17 @@ static void zend_lazy_object_revert_init(zend_object *obj, zval *properties_tabl
if (properties_snapshot) {
if (obj->properties != properties_snapshot) {
ZEND_ASSERT((GC_FLAGS(properties_snapshot) & IS_ARRAY_IMMUTABLE) || GC_REFCOUNT(properties_snapshot) >= 1);
zend_release_properties(obj->properties);
HashTable *garbage = obj->properties;
obj->properties = properties_snapshot;
zend_release_properties(garbage);
} else {
ZEND_ASSERT((GC_FLAGS(properties_snapshot) & IS_ARRAY_IMMUTABLE) || GC_REFCOUNT(properties_snapshot) > 1);
zend_release_properties(properties_snapshot);
}
} else if (obj->properties) {
zend_release_properties(obj->properties);
HashTable *garbage = obj->properties;
obj->properties = NULL;
zend_release_properties(garbage);
}

OBJ_EXTRA_FLAGS(obj) |= IS_OBJ_LAZY_UNINITIALIZED;
Expand Down Expand Up @@ -529,16 +542,27 @@ static zend_object *zend_lazy_object_init_proxy(zend_object *obj)

/* unset() properties of the proxy. This ensures that all accesses are be
* delegated to the backing instance from now on. */
zend_object_dtor_dynamic_properties(obj);
HashTable *garbage_ht = obj->properties;
obj->properties = NULL;
zend_release_properties(garbage_ht);

for (int i = 0; i < Z_OBJ(retval)->ce->default_properties_count; i++) {
zend_property_info *prop_info = Z_OBJ(retval)->ce->properties_info_table[i];
if (EXPECTED(prop_info)) {
zval *prop = &obj->properties_table[OBJ_PROP_TO_NUM(prop_info->offset)];
zend_object_dtor_property(obj, prop);
zval garbage;
ZVAL_COPY_VALUE(&garbage, prop);
ZVAL_UNDEF(prop);
Z_PROP_FLAG_P(prop) = IS_PROP_UNINIT | IS_PROP_LAZY;
if (Z_REFCOUNTED(garbage)) {
if (UNEXPECTED(Z_ISREF(garbage)) &&
(ZEND_DEBUG || ZEND_REF_HAS_TYPE_SOURCES(Z_REF(garbage)))) {
if (ZEND_TYPE_IS_SET(prop_info->type)) {
ZEND_REF_DEL_TYPE_SOURCE(Z_REF(garbage), prop_info);
}
}
i_zval_ptr_dtor(&garbage);
}
}
}

Expand Down
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