eldbus: check message serial before using

Summary:
Whatever the dbus_connection_send_with_reply returns, the serial value
should be checked, because if the seral value is invalid a process could be aborted.

There is backtrace as below.

The dbus_connection_send_with_reply could return TRUE
even though it has a problem. Please refer to following comment:

   /* Refuse to send fds on a connection that cannot handle
      them. Unfortunately we cannot return a proper error here, so
      the best we can do is return TRUE but leave *pending_return
      as NULL. */

Test Plan:
There is not a exact reproduce step. If the Tizen login manager is relaunched
repeatedly, then the dbus and other service processes are relaunched.
If a service process tries to use dbus when the dbus has problem as above,
then it could be possilbe to get above backtrace.

Reviewers: raster, zehortigoza

Subscribers: cedric, jpeg

Differential Revision: https://phab.enlightenment.org/D5053

@fix

1 files changed, 21 insertions, 7 deletions

diff --git a/src/lib/eldbus/eldbus_pending.c b/src/lib/eldbus/eldbus_pending.c
index 69ea322fc7..ecf65db100 100644
--- a/src/lib/eldbus/eldbus_pending.c
+++ b/src/lib/eldbus/eldbus_pending.c
@@ -113,6 +113,20 @@ eldbus_connection_send(Eldbus_Connection *conn, Eldbus_Message *msg, Eldbus_Mess
    return pending;
 }
 
+Eldbus_Message *
+_eldbus_message_error_get(const Eldbus_Message *msg, const char *error_name, const char *error_msg)
+{
+   int32_t serial;
+
+   serial = dbus_message_get_serial(msg->dbus_msg);
+   if (serial == 0)
+     {
+        return NULL;
+     }
+
+   return eldbus_message_error_new(msg, error_name, error_msg);
+}
+
 /*
  * On success @param msg is unref'd or its ref is stolen by the returned
  * Eldbus_Pending.
@@ -152,15 +166,15 @@ _eldbus_connection_send(Eldbus_Connection *conn, Eldbus_Message *msg, Eldbus_Mes
                                         msg->dbus_msg,
                                         &pending->dbus_pending, timeout))
      {
-        error_msg = eldbus_message_error_new(msg, "org.enlightenment.DBus.NoConnection",
-                                            "Eldbus_Connection was closed.");
+        error_msg = _eldbus_message_error_get(msg, "org.enlightenment.DBus.NoConnection",
+                                              "Eldbus_Connection was closed.");
         eldbus_pending_dispatch(pending, error_msg);
         return NULL;
      }
    if (!pending->dbus_pending)
      {
-        error_msg = eldbus_message_error_new(msg, "org.enlightenment.DBus.Error",
-                                             "dbus_pending is NULL.");
+        error_msg = _eldbus_message_error_get(msg, "org.enlightenment.DBus.Error",
+                                              "dbus_pending is NULL.");
         eldbus_pending_dispatch(pending, error_msg);
         return NULL;
      }
@@ -168,9 +182,9 @@ _eldbus_connection_send(Eldbus_Connection *conn, Eldbus_Message *msg, Eldbus_Mes
      return pending;
 
    dbus_pending_call_cancel(pending->dbus_pending);
-   error_msg = eldbus_message_error_new(pending->msg_sent,
-                                       "org.enlightenment.DBus.Error",
-                                       "Error when try set callback to message.");
+   error_msg = _eldbus_message_error_get(pending->msg_sent,
+                                         "org.enlightenment.DBus.Error",
+                                         "Error when try set callback to message.");
    eldbus_pending_dispatch(pending, error_msg);
    return NULL;
 }