qtdemux: exit when protection caps are not defined during PIFF parsing

Reproduction testcase (uses PlayReady):
https://developers.canal-plus.com/rx-player/upc/?appTileLocation=[object%20Object]

In test streams we are using PIFF box, but caps did not had
present GST_PROTECTION_SYSTEM_ID_CAPS_FIELD. In consequence, invalid
system_id was returned which caused SIGSEGV crash.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3535>

diff --git a/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c b/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
index 4e651b2..2d1887a 100644 (file)
--- a/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
+++ b/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
@@ -2843,8 +2843,13 @@ qtdemux_parse_piff (GstQTDemux * qtdemux, const guint8 * buffer, gint length,
     return;
   }
 
-  gst_structure_get (structure, GST_PROTECTION_SYSTEM_ID_CAPS_FIELD,
-      G_TYPE_STRING, &system_id, NULL);
+  if (!gst_structure_get (structure, GST_PROTECTION_SYSTEM_ID_CAPS_FIELD,
+          G_TYPE_STRING, &system_id, NULL)) {
+    GST_WARNING_OBJECT (qtdemux, "%s field not present in caps",
+        GST_PROTECTION_SYSTEM_ID_CAPS_FIELD);
+    return;
+  }
+
   gst_qtdemux_append_protection_system_id (qtdemux, system_id);
 
   stream->protected = TRUE;