qtdemux: prevent buffer flow if any stream failed to be exposed

In some cases the stream configuration can fail, for instance if the
stream is protected and no decryptor was found. For those situations
the demuxer shouldn't emit any data on the corresponding source pad of
the stream and bail out.

https://bugzilla.gnome.org/show_bug.cgi?id=762516

gst/isomp4/qtdemux.c

@@ -7145,6 +7145,7 @@ static gboolean
 gst_qtdemux_add_stream (GstQTDemux * qtdemux,
     QtDemuxStream * stream, GstTagList * list)
 {
+  gboolean ret = TRUE;
   /* consistent default for push based mode */
   gst_segment_init (&stream->segment, GST_FORMAT_TIME);
 
@@ -7155,7 +7156,13 @@ gst_qtdemux_add_stream (GstQTDemux * qtdemux,
         gst_pad_new_from_static_template (&gst_qtdemux_videosrc_template, name);
     g_free (name);
 
-    gst_qtdemux_configure_stream (qtdemux, stream);
+    if (!gst_qtdemux_configure_stream (qtdemux, stream)) {
+      gst_object_unref (stream->pad);
+      stream->pad = NULL;
+      ret = FALSE;
+      goto done;
+    }
+
     qtdemux->n_video_streams++;
   } else if (stream->subtype == FOURCC_soun) {
     gchar *name = g_strdup_printf ("audio_%u", qtdemux->n_audio_streams);
@@ -7163,7 +7170,12 @@ gst_qtdemux_add_stream (GstQTDemux * qtdemux,
     stream->pad =
         gst_pad_new_from_static_template (&gst_qtdemux_audiosrc_template, name);
     g_free (name);
-    gst_qtdemux_configure_stream (qtdemux, stream);
+    if (!gst_qtdemux_configure_stream (qtdemux, stream)) {
+      gst_object_unref (stream->pad);
+      stream->pad = NULL;
+      ret = FALSE;
+      goto done;
+    }
     qtdemux->n_audio_streams++;
   } else if (stream->subtype == FOURCC_strm) {
     GST_DEBUG_OBJECT (qtdemux, "stream type, not creating pad");
@@ -7174,7 +7186,12 @@ gst_qtdemux_add_stream (GstQTDemux * qtdemux,
     stream->pad =
         gst_pad_new_from_static_template (&gst_qtdemux_subsrc_template, name);
     g_free (name);
-    gst_qtdemux_configure_stream (qtdemux, stream);
+    if (!gst_qtdemux_configure_stream (qtdemux, stream)) {
+      gst_object_unref (stream->pad);
+      stream->pad = NULL;
+      ret = FALSE;
+      goto done;
+    }
     qtdemux->n_sub_streams++;
   } else if (stream->caps) {
     gchar *name = g_strdup_printf ("video_%u", qtdemux->n_video_streams);
@@ -7182,7 +7199,12 @@ gst_qtdemux_add_stream (GstQTDemux * qtdemux,
     stream->pad =
         gst_pad_new_from_static_template (&gst_qtdemux_videosrc_template, name);
     g_free (name);
-    gst_qtdemux_configure_stream (qtdemux, stream);
+    if (!gst_qtdemux_configure_stream (qtdemux, stream)) {
+      gst_object_unref (stream->pad);
+      stream->pad = NULL;
+      ret = FALSE;
+      goto done;
+    }
     qtdemux->n_video_streams++;
   } else {
     GST_DEBUG_OBJECT (qtdemux, "unknown stream type");
@@ -7211,7 +7233,7 @@ gst_qtdemux_add_stream (GstQTDemux * qtdemux,
 done:
   if (list)
     gst_tag_list_unref (list);
-  return TRUE;
+  return ret;
 }
 
 /* find next atom with @fourcc starting at @offset */
@@ -10606,7 +10628,8 @@ qtdemux_expose_streams (GstQTDemux * qtdemux)
     stream->pending_tags = NULL;
     if (oldpad)
       oldpads = g_slist_prepend (oldpads, oldpad);
-    gst_qtdemux_add_stream (qtdemux, stream, list);
+    if (!gst_qtdemux_add_stream (qtdemux, stream, list))
+      return GST_FLOW_ERROR;
   }
 
   gst_qtdemux_guess_bitrate (qtdemux);