Re: [PATCH v2] x86/boot: Rename overlapping memcpy() to memmove()

[Ingo Molnar <mingo@kernel.org>]

* Kees Cook <keescook@chromium.org> wrote:

> On Thu, Apr 28, 2016 at 9:47 AM, One Thousand Gnomes
> <gnomes@lxorguk.ukuu.org.uk> wrote:
> > O> For example, this is what I've got currently:
> >>
> >> /* Detect and warn about potential overlaps. */
> >> void *memcpy(void *dest, const void *src, size_t n)
> >> {
> >>         if (dest > src && dest - src < n)
> >>                 warn("Potentially unsafe overlapping memcpy detected!");
> >>         return __memcpy(dest, src, n);
> >> }
> >>
> >> Does that seem okay? If so, I'll send the patch...
> >
> > Probably useful for debug, but instead of relying on __memcpy
> > happening to handle overlaps - which isn't portable you could instead
> > debug all platforms by doing
> >
> >         if (...) {
> >                 warn(...)
> >                 memmove()
> >         } else
> >                 __memcpy
> >
> 
> Yeah, that's kind of where we started (but without the warning). I
> prefer this, since we don't run the risk of MAYBE breaking. We warn,
> but we remain safe.

Works for me!

Thanks,

	Ingo