Re: [Ksummit-discuss] [MAINTAINERS SUMMIT] API replacement/deprecation

[Kees Cook <keescook@chromium.org>]

On Fri, Sep 7, 2018 at 7:33 AM, Theodore Y. Ts'o <tytso@mit.edu> wrote:
> On Thu, Sep 06, 2018 at 04:24:03PM -0700, Kees Cook wrote:
>>
>> Hopefully we can all agree on deprecating strcpy() and strncpy() in
>> favor of strscpy()?
>
> There are some places where I use strncpy for a character array which
> is *not* a null-terminated string.  What is the preferred alternative
> for me?  I can suppress the problem when gcc complains about it using:
>
> +       __u8    s_first_error_func[32] __nonstring;     /* function where the error happened */
>
> But if we do a blanket deprecation, what should I use instead?

strncpy() is a weird one. I think we can easily say "no strcpy()" but
for strncpy() we need to examine the existing use-cases:

- non-NUL-terminated: use memcpy?
- NEEDS trailing NUL padding: ... no solution yet. invent strscpy_pad() ?
- "safe" strcpy(): use strscpy()

-Kees

-- 
Kees Cook
Pixel Security