Gimp: unbounded stack vla and 21-byte stack over-read in pix (esm) loader

A flaw was found in the file-pix (ESM) plugin in GIMP. When processing a specially crafted PIX image file, the plugin allocates a Variable-Length Array (VLA) on the stack without proper bounds checking, causing an unbounded stack allocation followed by a 21-byte stack over-read. This can result in a denial of service due to stack exhaustion and a limited information disclosure of stack memory contents into an intermediate file.