Re: [PATCH v4 1/4] lib/ucs2_string: Add UCS-2 strlcpy function

[Kees Cook <keescook@chromium.org>]

On Tue, May 30, 2023 at 06:17:35PM +0200, Ard Biesheuvel wrote:
> On Tue, 30 May 2023 at 18:15, Maximilian Luz <luzmaximilian@gmail.com> wrote:
> >
> > On 5/30/23 17:25, Kees Cook wrote:
> > > On Mon, May 29, 2023 at 01:03:48AM +0200, Maximilian Luz wrote:
> > >> Add a ucs2_strlcpy() function for UCS-2 strings. The behavior is
> > >> equivalent to the standard strlcpy() function, just for 16-bit character
> > >> UCS-2 strings.
> > >
> > > Eek, no. strlcpy() is dangerous in multiple ways[1]. Please implement
> > > strscpy() (i.e. use strnlen(), negative error on truncation, etc).
> >
> > Right, make sense, thanks. Somehow I missed that the kernel has a better
> > function than the C stdlib for that...
> >
> > > Additionally, it'd be nice of the ucs2 helpers here also implemented the
> > > rest of the CONFIG_FORTIFY_SOURCE mitigations (i.e. checking for source
> > > and destination buffer size overflows at compile-time and run-time with
> > > __builtin_object_size() and __builtin_dynamoc_object_size() respectively).
> >
> > I can certainly try that, but I think this might be better suited for a
> > follow-up series, given that we then should also add those to the other
> > helpers.
> >
> 
> Agreed. Let's log the followup work as a kspp work item, no need to
> make that part of this series.

Yeah, that's fine. Can you please open a KSSP issue for it so we don't
forget?  :)

-- 
Kees Cook