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.