Re: [PATCH] hamradio: replace deprecated strncpy with strscpy

[Hugh Blemings]

On 17/10/23 04:03, Kees Cook wrote:
> On October 16, 2023 10:01:20 AM PDT, Kees Cook <kees@xxxxxxxxxx> wrote:
> > On October 15, 2023 10:47:53 PM PDT, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> > > On Sun, Oct 15, 2023 at 05:06:19PM +0200, Simon Horman wrote:
> > > > On Thu, Oct 12, 2023 at 09:33:32PM +0000, Justin Stitt wrote:
> > > > > strncpy() is deprecated for use on NUL-terminated destination strings
> > > > > [1] and as such we should prefer more robust and less ambiguous string
> > > > > interfaces.
> > > > >
> > > > > We expect both hi.data.modename and hi.data.drivername to be
> > > > > NUL-terminated but not necessarily NUL-padded which is evident by its
> > > > > usage with sprintf:
> > > > > |       sprintf(hi.data.modename, "%sclk,%smodem,fclk=%d,bps=%d%s",
> > > > > |               bc->cfg.intclk ? "int" : "ext",
> > > > > |               bc->cfg.extmodem ? "ext" : "int", bc->cfg.fclk, bc->cfg.bps,
> > > > > |               bc->cfg.loopback ? ",loopback" : "");
> > > > >
> > > > > Note that this data is copied out to userspace with:
> > > > > |       if (copy_to_user(data, &hi, sizeof(hi)))
> > > > > ... however, the data was also copied FROM the user here:
> > > > > |       if (copy_from_user(&hi, data, sizeof(hi)))
> > > >
> > > > Thanks Justin,
> > > >
> > > > I see that too.
> > > >
> > > > Perhaps I am off the mark here, and perhaps it's out of scope for this
> > > > patch, but I do think it would be nicer if the kernel only sent
> > > > intended data to user-space, even if any unintended payload came
> > > > from user-space.
> > >
> > > It's kind of normal to pass user space data back to itself.  We
> > > generally only worry about info leaks.
> >
> > True but since this used to zero the rest of the buffet, let's just keep that behavior and use strscpy_pad().
>
> I'm calling all byte arrays a "buffet" from now on. ;)
A tasteful change to the sauce I think.  ;)