From de2fd24e776b2d290a86d7e560082e4c223cbf7a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Javier=20Jaramago=20Fern=C3=A1ndez?=
 <jaramago.fernandez.javier@gmail.com>
Date: Fri, 30 Jul 2021 13:33:24 +0200
Subject: [PATCH] Fix leak closing 'query.stmt' in case of 'async_free_result'
 called for 'ASYNC_STMT_PREPARE_FAILED' state #3525

---
 lib/mysql_connection.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/mysql_connection.cpp b/lib/mysql_connection.cpp
index 7589798e7..3a5b12659 100644
--- a/lib/mysql_connection.cpp
+++ b/lib/mysql_connection.cpp
@@ -2145,6 +2145,15 @@ void MySQL_Connection::async_free_result() {
 					mysql_stmt_free_result(query.stmt);
 				}
 			}
+			// If we reached here from 'ASYNC_STMT_PREPARE_FAILED', the
+			// prepared statement was never added to 'local_stmts', thus
+			// it will never be freed when 'local_stmts' are purged. If
+			// initialized, it must be freed. For more context see #3525.
+			if (this->async_state_machine == ASYNC_STMT_PREPARE_FAILED) {
+				if (query.stmt != NULL) {
+					mysql_stmt_close(query.stmt);
+				}
+			}
 			query.stmt=NULL;
 		}
 		if (mysql_result) {