mssdemux: fix reverse playback fragment tracking

Rework reverse fragment traversing with repetition fields to prevent
NULL pointer deref and avoid never advancing a fragment as the variable
is unsigned and would always be non-negative.

CID #1257627
CID #1257628

1 files changed, 8 insertions, 9 deletions

diff --git a/ext/smoothstreaming/gstmssmanifest.c b/ext/smoothstreaming/gstmssmanifest.c
index 88c700054..2ee0f3129 100644
--- a/ext/smoothstreaming/gstmssmanifest.c
+++ b/ext/smoothstreaming/gstmssmanifest.c
@@ -986,16 +986,15 @@ gst_mss_stream_regress_fragment (GstMssStream * stream)
     return GST_FLOW_EOS;
 
   fragment = stream->current_fragment->data;
-  stream->fragment_repetition_index--;
-  if (stream->fragment_repetition_index >= 0) {
-    return GST_FLOW_OK;
+  if (stream->fragment_repetition_index == 0) {
+    stream->current_fragment = g_list_previous (stream->current_fragment);
+    if (stream->current_fragment == NULL)
+      return GST_FLOW_EOS;
+    fragment = stream->current_fragment->data;
+    stream->fragment_repetition_index = fragment->repetitions - 1;
+  } else {
+    stream->fragment_repetition_index--;
   }
-
-  stream->current_fragment = g_list_previous (stream->current_fragment);
-  fragment = stream->current_fragment->data;
-  if (stream->current_fragment == NULL)
-    return GST_FLOW_EOS;
-  stream->fragment_repetition_index = fragment->repetitions - 1;
   return GST_FLOW_OK;
 }