gst_qtdemux_loop_state_header (GstQTDemux * qtdemux)
{
  guint64 length;
  guint32 fourcc;
  GstBuffer *buf = NULL;
  GstFlowReturn ret = GST_FLOW_OK;
  guint64 cur_offset = qtdemux->offset;

  ret = gst_pad_pull_range (qtdemux->sinkpad, cur_offset, 16, &buf);
  if (ret != GST_FLOW_OK)
    goto beach;
  extract_initial_length_and_fourcc (GST_BUFFER_DATA (buf), &length, &fourcc);
  gst_buffer_unref (buf);

  if (length == 0) {
    GST_ELEMENT_ERROR (qtdemux, STREAM, DECODE,
        (_("This file is invalid and cannot be played.")),
        ("Header atom '%" GST_FOURCC_FORMAT "' has empty length",
            GST_FOURCC_ARGS (fourcc)));
    ret = GST_FLOW_ERROR;
    goto beach;
  }

  switch (fourcc) {
    case FOURCC_mdat:
    case FOURCC_free:
    case FOURCC_wide:
    case FOURCC_PICT:
    case FOURCC_pnot:
    {
      GST_LOG_OBJECT (qtdemux,
          "skipping atom '%" GST_FOURCC_FORMAT "' at %" G_GUINT64_FORMAT,
          GST_FOURCC_ARGS (fourcc), cur_offset);
      cur_offset += length;
      qtdemux->offset += length;
      break;
    }
    case FOURCC_moov:
    {
      GstBuffer *moov;

      ret = gst_pad_pull_range (qtdemux->sinkpad, cur_offset, length, &moov);
      if (ret != GST_FLOW_OK)
        goto beach;
      if (length != GST_BUFFER_SIZE (moov)) {
        /* Some files have a 'moov' atom at the end of the file which contains
         * a terminal 'free' atom where the body of the atom is missing.
         * Check for, and permit, this special case.
         */
        if (GST_BUFFER_SIZE (moov) >= 8) {
          guint8 *final_data = GST_BUFFER_DATA (moov) +
              (GST_BUFFER_SIZE (moov) - 8);
          guint32 final_length = QT_UINT32 (final_data);
          guint32 final_fourcc = QT_FOURCC (final_data + 4);
          if (final_fourcc == FOURCC_free &&
              GST_BUFFER_SIZE (moov) + final_length - 8 == length) {
            /* Ok, we've found that special case. Allocate a new buffer with
             * that free atom actually present. */
            GstBuffer *newmoov = gst_buffer_new_and_alloc (length);
            gst_buffer_copy_metadata (newmoov, moov,
                GST_BUFFER_COPY_FLAGS | GST_BUFFER_COPY_TIMESTAMPS |
                GST_BUFFER_COPY_CAPS);
            memcpy (GST_BUFFER_DATA (newmoov), GST_BUFFER_DATA (moov),
                GST_BUFFER_SIZE (moov));
            memset (GST_BUFFER_DATA (newmoov) + GST_BUFFER_SIZE (moov), 0,
                final_length - 8);
            gst_buffer_unref (moov);
            moov = newmoov;
          }
        }
      }

      if (length != GST_BUFFER_SIZE (moov)) {
        GST_ELEMENT_ERROR (qtdemux, STREAM, DECODE,
            (_("This file is incomplete and cannot be played.")),
            ("We got less than expected (received %u, wanted %u, offset %"
                G_GUINT64_FORMAT ")",
                GST_BUFFER_SIZE (moov), (guint) length, cur_offset));
        ret = GST_FLOW_ERROR;
        goto beach;
      }
      cur_offset += length;
      qtdemux->offset += length;

      qtdemux_parse_moov (qtdemux, GST_BUFFER_DATA (moov), length);
      qtdemux_node_dump (qtdemux, qtdemux->moov_node);

      qtdemux_parse_tree (qtdemux);
      g_node_destroy (qtdemux->moov_node);
      gst_buffer_unref (moov);
      qtdemux->moov_node = NULL;
      qtdemux->state = QTDEMUX_STATE_MOVIE;
      GST_DEBUG_OBJECT (qtdemux, "switching state to STATE_MOVIE (%d)",
          qtdemux->state);
      break;
    }
    case FOURCC_ftyp:
    {
      GstBuffer *ftyp;

      /* extract major brand; might come in handy for ISO vs QT issues */
      ret = gst_pad_pull_range (qtdemux->sinkpad, cur_offset, length, &ftyp);
      if (ret != GST_FLOW_OK)
        goto beach;
      cur_offset += length;
      qtdemux->offset += length;
      /* only consider at least a sufficiently complete ftyp atom */
      if (length >= 20) {
        qtdemux->major_brand = QT_FOURCC (GST_BUFFER_DATA (ftyp) + 8);
        GST_DEBUG_OBJECT (qtdemux, "major brand: %" GST_FOURCC_FORMAT,
            GST_FOURCC_ARGS (qtdemux->major_brand));
      }
      gst_buffer_unref (ftyp);
      break;
    }
    default:
    {
      GST_LOG_OBJECT (qtdemux,
          "unknown %08x '%" GST_FOURCC_FORMAT "' at %" G_GUINT64_FORMAT, fourcc,
          GST_FOURCC_ARGS (fourcc), cur_offset);
      cur_offset += length;
      qtdemux->offset += length;
      break;
    }
  }

beach:
  return ret;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.