fix null pointer deref

diff --git a/ext/mysqlnd/mysqlnd.c b/ext/mysqlnd/mysqlnd.c
index f6a3fffac8c6d36b5b48408c661950445c7abc56..74a8b721f22aa571dfc608373ff72c94dbb39c36 100644 (file)
--- a/ext/mysqlnd/mysqlnd.c
+++ b/ext/mysqlnd/mysqlnd.c
@@ -2804,12 +2804,12 @@ MYSQLND_METHOD(mysqlnd_conn_data, tx_begin)(MYSQLND_CONN_DATA * conn, const unsi
                                        smart_str_free(&tmp_str);
                                        break;
                                } else if (mode & TRANS_START_READ_WRITE) {
-                                       if (tmp_str.s->len) {
+                                       if (tmp_str.s && tmp_str.s->len) {
                                                smart_str_appendl(&tmp_str, ", ", sizeof(", ") - 1);
                                        }
                                        smart_str_appendl(&tmp_str, "READ WRITE", sizeof("READ WRITE") - 1);
                                } else if (mode & TRANS_START_READ_ONLY) {
-                                       if (tmp_str.s->len) {
+                                       if (tmp_str.s && tmp_str.s->len) {
                                                smart_str_appendl(&tmp_str, ", ", sizeof(", ") - 1);
                                        }
                                        smart_str_appendl(&tmp_str, "READ ONLY", sizeof("READ ONLY") - 1);