gimp: gimp: heap out-of-bounds read/write in PSD thumbnail loader (load_resource_1033)

A flaw was found in GIMP. The PSD thumbnail resource loader performs a BGR-to-RGB channel swap with a fixed 3-byte stride and does not verify that the JPEG thumbnail is RGB. A crafted grayscale PSD thumbnail can cause a heap out-of-bounds read and write in the plug-in process, leading to a crash...