GHSL-2024-249: GStreamer has a NULL-pointer dereference in Matroska/WebM demuxer

GStreamer is a library for constructing graphs of media-handling components. A null pointer dereference vulnerability has been discovered in the gst_matroska_demux_parse_blockgroup_or_simpleblock function within matroska-demux.c. This function does not properly check the validity of the GstBuffer *sub pointer before performing dereferences. As a result, null pointer dereferences may occur. This vulnerability is fixed in 1.24.10.