Bug#33300587: mysqld crash with unknown parameter and enable create_a…

…dmin_listener_thread

Problem: Attempting to start mysqld with
--create_admin_listener_thread and an illegal parameter resulted in a
SEGV.

Solution: Make sure cleanup code checks to see if admin thread has
actually been created before trying to pthread_kill it.

Change-Id: Ia0d2dab33da7093118f4f3e929d9cb38494f6fe8

include/my_thread.h

@@ -147,6 +147,17 @@ static inline void my_thread_yield() {
 #endif
 }
 
+inline bool operator==(const my_thread_handle &a, const my_thread_handle &b) {
+  return (a.thread == b.thread
+#ifdef WIN32
+          && a.handle == b.handle
+#endif /* WIN32 */
+  );
+}
+inline bool operator!=(const my_thread_handle &a, const my_thread_handle &b) {
+  return !(a == b);
+}
+
 int my_thread_create(my_thread_handle *thread, const my_thread_attr_t *attr,
                      my_start_routine func, void *arg);
 int my_thread_join(my_thread_handle *thread, void **value_ptr);

sql/conn_handler/socket_connection.cc

@@ -1444,28 +1444,36 @@ void Mysqld_socket_listener::close_listener() {
     referenced by the data member m_admin_interface_listen_socket.
   */
   if (m_use_separate_thread_for_admin) {
+    if (admin_socket_thread_id != my_thread_handle{}) {
 #ifdef _WIN32
-    /*
-      For Windows, first close the socket referenced by the data member
-      m_admin_interface_listen_socket. It results in return from select()
-      API call running from a separate thread.
-    */
-    (void)mysql_socket_close(m_admin_interface_listen_socket);
-    my_thread_join(&admin_socket_thread_id, nullptr);
+      /*
+        For Windows, first close the socket referenced by the data member
+        m_admin_interface_listen_socket. It results in return from select()
+        API call running from a separate thread.
+      */
+      (void)mysql_socket_close(m_admin_interface_listen_socket);
+      m_admin_interface_listen_socket.fd = INVALID_SOCKET;
+      my_thread_join(&admin_socket_thread_id, nullptr);
 #else
-    // First, finish listening thread.
-    pthread_kill(admin_socket_thread_id.thread, SIGALRM);
-    my_thread_join(&admin_socket_thread_id, nullptr);
+      // First, finish listening thread.
+      pthread_kill(admin_socket_thread_id.thread, SIGALRM);
+      my_thread_join(&admin_socket_thread_id, nullptr);
+
+#endif
+      mysql_mutex_destroy(&LOCK_start_admin_thread);
+      mysql_cond_destroy(&COND_start_admin_thread);
+    }  // if (admin_socket_thread_id != my_thread_handle{})
     /*
       After a thread listening on admin interface finished, it is safe
-      to close listening socket.
+      to close listening socket. But socket is opened before thread is
+      spawned, so we may need to close the socket even if
+      admin_socket_thread_id has not been assigned.
     */
-    (void)mysql_socket_close(m_admin_interface_listen_socket);
-#endif
-
-    mysql_mutex_destroy(&LOCK_start_admin_thread);
-    mysql_cond_destroy(&COND_start_admin_thread);
-  }
+    if (m_admin_interface_listen_socket.fd != INVALID_SOCKET) {
+      (void)mysql_socket_close(m_admin_interface_listen_socket);
+      m_admin_interface_listen_socket.fd = INVALID_SOCKET;
+    }
+  }  // use_separate_thread_for_admin
 
 #if defined(HAVE_SYS_UN_H)
   if (m_unix_sockname != "" && m_unlink_sockname) {