Add a regression test that builds a FIT with external data, inflates the data-size property far beyond the image and any plausible load region, and confirms that spl_load_simple_fit() returns -EFBIG instead of reading the declared size off the device. Without the bounds check in load_simple_fit() this test overruns memory and crashes; with it the load is rejected cleanly. Signed-off-by: Aristo Chen <aristo.chen@canonical.com> Reviewed-by: Simon Glass <sjg@chromium.org>