CVE-2023-45666

stb_image is a single file MIT licensed library for processing images. It
may look like stbi__load_gif_main doesn’t give guarantees about the
content of output value *delays upon failure. Although it sets *delays
to zero at the beginning, it doesn’t do it in case the image is not
recognized as GIF and a call to stbi__load_gif_main_outofmem only frees
possibly allocated memory in *delays without resetting it to zero. Thus
it would be fair to say the caller of stbi__load_gif_main is responsible
to free the allocated memory in *delays only if stbi__load_gif_main
returns a non null value. However at the same time the function may return
null value, but fail to free the memory in *delays if internally
stbi__convert_format is called and fails. Thus the issue may lead to a
memory leak if the caller chooses to free delays only when
stbi__load_gif_main didn’t fail or to a double-free if the delays is
always freed