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Fix GH-21831: Defer removals during SplObjectStorage::removeAllExcept() #21835

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Fix GH-21831: Defer removals during SplObjectStorage::removeAllExcept() #21835

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9c3d110
Fix GH-21831: Defer removals during SplObjectStorage::removeAllExcept()
prateekbhujel Apr 23, 2026
c261f36
ext/spl: Guard empty deferred removal list
prateekbhujel Apr 23, 2026
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19 changes: 18 additions & 1 deletion ext/spl/spl_observer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -633,22 +633,39 @@ PHP_METHOD(SplObjectStorage, removeAllExcept)
spl_SplObjectStorage *intern = Z_SPLOBJSTORAGE_P(ZEND_THIS);
spl_SplObjectStorage *other;
spl_SplObjectStorageElement *element;
zend_object **to_remove = NULL;
uint32_t to_remove_count = 0;
uint32_t to_remove_capacity = 0;

if (zend_parse_parameters(ZEND_NUM_ARGS(), "O", &obj, spl_ce_SplObjectStorage) == FAILURE) {
RETURN_THROWS();
}

other = Z_SPLOBJSTORAGE_P(obj);

/* Avoid mutating this storage while other->getHash() may re-enter it. */
SPL_SAFE_HASH_FOREACH_PTR(&intern->storage, element) {
zend_object *elem_obj = element->obj;
GC_ADDREF(elem_obj);
if (!spl_object_storage_contains(other, elem_obj)) {
spl_object_storage_detach(intern, elem_obj);
if (to_remove_count == to_remove_capacity) {
to_remove_capacity = to_remove_capacity ? to_remove_capacity * 2 : 8;
to_remove = safe_erealloc(to_remove, to_remove_capacity, sizeof(zend_object *), 0);
}
to_remove[to_remove_count++] = elem_obj;
continue;
}
OBJ_RELEASE(elem_obj);
} ZEND_HASH_FOREACH_END();

for (uint32_t i = 0; i < to_remove_count; i++) {
spl_object_storage_detach(intern, to_remove[i]);
OBJ_RELEASE(to_remove[i]);
}
if (to_remove) {
efree(to_remove);
}

zend_hash_internal_pointer_reset_ex(&intern->storage, &intern->pos);
intern->index = 0;

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31 changes: 31 additions & 0 deletions ext/spl/tests/SplObjectStorage/gh21831.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,31 @@
--TEST--
GH-21831: SplObjectStorage::removeAllExcept() tolerates re-entrant deletion in getHash()
--FILE--
<?php

class FilterStorage extends SplObjectStorage {
public ?SplObjectStorage $other = null;

public function getHash($obj): string {
if ($this->other) {
$this->other->offsetUnset($obj);
$this->other = null;
}

return 'x';
}
}

$storage = new SplObjectStorage();
$storage[new stdClass()] = null;

$filter = new FilterStorage();
$filter->other = $storage;

var_dump($storage->removeAllExcept($filter));
var_dump(count($storage));

?>
--EXPECT--
int(0)
int(0)
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