Re: [PATCH v4] exec: load_script: Do not exec truncated interpreter path

[Linus Torvalds]

On Sun, Feb 17, 2019 at 1:09 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> +static inline char *next_spacetab(char *first, const char *last)
> +{
> +       for (; first <= last; first++)
> +               if (spacetab(*first))
> +                       return first;
> +       return NULL;
> +}

I think this should be "next_terminator()" and also stop at NUL.

You do check for the NUL case here:

> +               if (!next_spacetab(cp, buf_end) && *buf_end)
> +                       return -ENOEXEC;

but it means that if there's no space ot tab and it's a short file,
you pointlessly walk to the end. No?

                   Linus