Re: [PATCH 1/2] x86: math-emu: check __copy_from_user result

[Arnd Bergmann]

On Wed, Oct 2, 2019 at 1:39 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote:

> > diff --git a/arch/x86/math-emu/reg_ld_str.c b/arch/x86/math-emu/reg_ld_str.c
> > index f3779743d15e..fe6246ff9887 100644
> > --- a/arch/x86/math-emu/reg_ld_str.c
> > +++ b/arch/x86/math-emu/reg_ld_str.c
> > @@ -85,7 +85,7 @@ int FPU_load_extended(long double __user *s, int stnr)
> >
> >       RE_ENTRANT_CHECK_OFF;
> >       FPU_access_ok(s, 10);
> > -     __copy_from_user(sti_ptr, s, 10);
> > +     FPU_copy_from_user(sti_ptr, s, 10);
>
> These access_ok() checks seem redundant everywhere in this file (after
> your switch from __copy* to copy*. I mean, I guess, just leave them, but
> *shrug*

There have always been duplicate/inconsistent for the get_user/put_user
case. I considered cleaning it all up but then decided to touch it as little
as possible.

       Arnd