Gimp: heap out-of-bounds read in ico loader via unvalidated used_clrs palette count

A flaw was found in the file-ico plugin in GIMP. When processing a specially crafted ICO image file, the plugin does not properly validate the used_clrs (palette count) parameter. This incorrect validation leads to improper memory bounds checking, resulting in 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.