Re: [PATCH v4] libbpf: Replace strncpy() with strnlen()+memcpy() in skel_map_create()

[Alexei Starovoitov]

On Fri, Apr 3, 2026 at 8:54 AM Kees Cook <kees@xxxxxxxxxx> wrote:
> > > -       strncpy(attr.map_name, map_name, sizeof(attr.map_name));
> > > +       /* attr.map_name must be NUL-terminated, like bpf_obj_name_cpy() */
> > > +       map_name_len = strnlen(map_name, sizeof(attr.map_name));
> > > +       if (map_name_len == sizeof(attr.map_name))
> > > +               return -EINVAL;
> > > +       memcpy(attr.map_name, map_name, map_name_len);
> >
> > this is plain ugly and inefficient.
> > Just #ifdef kernel and use strscpy in that branch.
>
> I think you're asking for:
>
> #ifdef __KERNEL__
>         if (strscpy(attr.map_name, map_name) < 0)
>                 return -EINVAL;
> #else
>         strncpy(attr.map_name, map_name, sizeof(attr.map_name));
> #endif
>
> Is that right?

yes.