fix Bug #62273 Segmentation Fault in Mysqli/Mysqlnd

ext/mysqlnd/mysqlnd.c

@@ -680,6 +680,13 @@ MYSQLND_METHOD(mysqlnd_conn, connect)(MYSQLND * conn,
 	conn->server_version	= mnd_pestrdup(greet_packet->server_version, conn->persistent);
 
 	conn->greet_charset = mysqlnd_find_charset_nr(greet_packet->charset_no);
+	if (!conn->greet_charset) {
+		php_error_docref(NULL TSRMLS_CC, E_WARNING,
+			"Server sent charset (%d) unknown to the client. Please, report to the developers", greet_packet->charset_no);
+		SET_CLIENT_ERROR(conn->error_info, CR_NOT_IMPLEMENTED, UNKNOWN_SQLSTATE,
+			"Server sent charset unknown to the client. Please, report to the developers");
+		goto err;
+	}
 	/* we allow load data local infile by default */
 	mysql_flags |= CLIENT_LOCAL_FILES | CLIENT_PS_MULTI_RESULTS;
 	mysql_flags |= MYSQLND_CAPABILITIES;