ext/pdo: Fix memory leak if GC needs to free PDO Statement

ext/pdo/pdo_stmt.c

@@ -2079,8 +2079,11 @@ static zend_function *dbstmt_method_get(zend_object **object_pp, zend_string *me
 static HashTable *dbstmt_get_gc(zend_object *object, zval **gc_data, int *gc_count)
 {
 	pdo_stmt_t *stmt = php_pdo_stmt_fetch_object(object);
-	*gc_data = &stmt->fetch.into;
-	*gc_count = 1;
+
+	zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
+	zend_get_gc_buffer_add_zval(gc_buffer, &stmt->database_object_handle);
+	zend_get_gc_buffer_add_zval(gc_buffer, &stmt->fetch.into);
+	zend_get_gc_buffer_use(gc_buffer, gc_data, gc_count);
 
 	/**
 	 * If there are no dynamic properties and the default property is 1 (that is, there is only one property

ext/pdo/tests/pdo_stmt_cyclic_references.phpt

@@ -0,0 +1,138 @@
+--TEST--
+PDO Common: Cyclic PDOStatement child class
+--EXTENSIONS--
+pdo
+--SKIPIF--
+<?php
+$dir = getenv('REDIR_TEST_DIR');
+if (false == $dir) die('skip no driver');
+require_once $dir . 'pdo_test.inc';
+PDOTest::skip();
+?>
+--FILE--
+<?php
+if (getenv('REDIR_TEST_DIR') === false) putenv('REDIR_TEST_DIR='.__DIR__ . '/../../pdo/tests/');
+require_once getenv('REDIR_TEST_DIR') . 'pdo_test.inc';
+
+class Ref {
+    public CyclicStatement $stmt;
+}
+
+class CyclicStatement extends PDOStatement {
+    protected function __construct(public Ref $ref) {}
+}
+
+class TestRow {
+    public $id;
+    public $val;
+    public $val2;
+
+    public function __construct(public string $arg) {}
+}
+
+$db = PDOTest::factory();
+$db->exec('CREATE TABLE pdo_stmt_cyclic_ref(id INT NOT NULL PRIMARY KEY, val VARCHAR(10), val2 VARCHAR(10))');
+$db->exec("INSERT INTO pdo_stmt_cyclic_ref VALUES(1, 'A', 'AA')");
+$db->exec("INSERT INTO pdo_stmt_cyclic_ref VALUES(2, 'B', 'BB')");
+$db->exec("INSERT INTO pdo_stmt_cyclic_ref VALUES(3, 'C', 'CC')");
+
+$db->setAttribute(PDO::ATTR_STATEMENT_CLASS, ['CyclicStatement', [new Ref]]);
+
+echo "Column fetch:\n";
+$stmt = $db->query('SELECT id, val2, val FROM pdo_stmt_cyclic_ref');
+$stmt->ref->stmt = $stmt;
+$stmt->setFetchMode(PDO::FETCH_COLUMN, 2);
+foreach($stmt as $obj) {
+    var_dump($obj);
+}
+
+echo "Class fetch:\n";
+$stmt = $db->query('SELECT id, val2, val FROM pdo_stmt_cyclic_ref');
+$stmt->ref->stmt = $stmt;
+$stmt->setFetchMode(PDO::FETCH_CLASS, 'TestRow', ['Hello world']);
+foreach($stmt as $obj) {
+    var_dump($obj);
+}
+
+echo "Fetch into:\n";
+$stmt = $db->query('SELECT id, val2, val FROM pdo_stmt_cyclic_ref');
+$stmt->ref->stmt = $stmt;
+$stmt->setFetchMode(PDO::FETCH_INTO, new TestRow('I am being fetch into'));
+foreach($stmt as $obj) {
+    var_dump($obj);
+}
+
+?>
+--CLEAN--
+<?php
+require_once getenv('REDIR_TEST_DIR') . 'pdo_test.inc';
+$db = PDOTest::factory();
+PDOTest::dropTableIfExists($db, "pdo_stmt_cyclic_ref");
+?>
+--EXPECTF--
+Column fetch:
+string(1) "A"
+string(1) "B"
+string(1) "C"
+Class fetch:
+object(TestRow)#%d (4) {
+  ["id"]=>
+  string(1) "1"
+  ["val"]=>
+  string(1) "A"
+  ["val2"]=>
+  string(2) "AA"
+  ["arg"]=>
+  string(11) "Hello world"
+}
+object(TestRow)#%d (4) {
+  ["id"]=>
+  string(1) "2"
+  ["val"]=>
+  string(1) "B"
+  ["val2"]=>
+  string(2) "BB"
+  ["arg"]=>
+  string(11) "Hello world"
+}
+object(TestRow)#%d (4) {
+  ["id"]=>
+  string(1) "3"
+  ["val"]=>
+  string(1) "C"
+  ["val2"]=>
+  string(2) "CC"
+  ["arg"]=>
+  string(11) "Hello world"
+}
+Fetch into:
+object(TestRow)#4 (4) {
+  ["id"]=>
+  string(1) "1"
+  ["val"]=>
+  string(1) "A"
+  ["val2"]=>
+  string(2) "AA"
+  ["arg"]=>
+  string(21) "I am being fetch into"
+}
+object(TestRow)#4 (4) {
+  ["id"]=>
+  string(1) "2"
+  ["val"]=>
+  string(1) "B"
+  ["val2"]=>
+  string(2) "BB"
+  ["arg"]=>
+  string(21) "I am being fetch into"
+}
+object(TestRow)#4 (4) {
+  ["id"]=>
+  string(1) "3"
+  ["val"]=>
+  string(1) "C"
+  ["val2"]=>
+  string(2) "CC"
+  ["arg"]=>
+  string(21) "I am being fetch into"
+}