Gimp: multiple heap out-of-bounds reads in xwd loader from unrelated width and bytes-per-line validation

A flaw was found in the file-xwd plugin in GIMP. When processing a specially crafted XWD image file, the plugin validates the image width and bytes-per-line parameters independently rather than ensuring their combined values are consistent with the allocated buffer size. This incorrect validation leads to improper bounds checking, causing a heap out-of-bounds read. This issue can result in an application crash, leading to a denial of service or a limited information disclosure of heap memory contents into the produced image.