file descriptor exhaustion (GHSL-2021-077)

Resolves: CVE-2021-4115

CVE-2021-4115.patch

+diff --git a/src/polkit/polkitsystembusname.c b/src/polkit/polkitsystembusname.c
+index 8ed1363..2fbf5f1 100644
+--- a/src/polkit/polkitsystembusname.c
++++ b/src/polkit/polkitsystembusname.c
+@@ -62,6 +62,10 @@ enum
+   PROP_NAME,
+ };
+ 
++
++guint8 dbus_call_respond_fails;      // has to be global because of callback
++
++
+ static void subject_iface_init (PolkitSubjectIface *subject_iface);
+ 
+ G_DEFINE_TYPE_WITH_CODE (PolkitSystemBusName, polkit_system_bus_name, G_TYPE_OBJECT,
+@@ -364,6 +368,7 @@ on_retrieved_unix_uid_pid (GObject              *src,
+   if (!v)
+     {
+       data->caught_error = TRUE;
++      dbus_call_respond_fails += 1;
+     }
+   else
+     {
+@@ -405,6 +410,8 @@ polkit_system_bus_name_get_creds_sync (PolkitSystemBusName           *system_bus
+   tmp_context = g_main_context_new ();
+   g_main_context_push_thread_default (tmp_context);
+ 
++  dbus_call_respond_fails = 0;
++
+   /* Do two async calls as it's basically as fast as one sync call.
+    */
+   g_dbus_connection_call (connection,
+@@ -432,11 +439,34 @@ polkit_system_bus_name_get_creds_sync (PolkitSystemBusName           *system_bus
+ 			  on_retrieved_unix_uid_pid,
+ 			  &data);
+ 
+-  while (!((data.retrieved_uid && data.retrieved_pid) || data.caught_error))
+-    g_main_context_iteration (tmp_context, TRUE);
++  while (TRUE)
++  {
++    /* If one dbus call returns error, we must wait until the other call
++     * calls _call_finish(), otherwise fd leak is possible.
++     * Resolves: GHSL-2021-077
++    */
+ 
+-  if (data.caught_error)
+-    goto out;
++    if ( (dbus_call_respond_fails > 1) )
++    {
++      // we got two faults, we can leave
++      goto out;
++    }
++
++    if ((data.caught_error && (data.retrieved_pid || data.retrieved_uid)))
++    {
++      // we got one fault and the other call finally finished, we can leave
++      goto out;
++    }
++
++    if ( !(data.retrieved_uid && data.retrieved_pid) )
++    {
++      g_main_context_iteration (tmp_context, TRUE);
++    }
++    else
++    {
++      break;
++    }
++  }
+ 
+   if (out_uid)
+     *out_uid = data.uid;