Gimp: heap out-of-bounds read and stack out-of-bounds access in psd loader from channel-count handling

A flaw was found in the file-psd plugin in GIMP. When processing a specially crafted PSD image file, the plugin does not properly validate the channel-count parameter. This incorrect validation leads to improper memory bounds checking, resulting in both a heap out-of-bounds read and a stack out-of-bounds access. This issue can result in an application crash, leading to a denial of service or a limited information disclosure of memory contents.