linux-kernel - Re: [PATCH 1/2] x86: math-emu: check __copy_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAK8P3a2BKyz8Myrd-ob9t5FyJmQ_FVUmNMYbfzr6YUZWfyH4XQ@mail.gmail.com>
Date:   Wed, 2 Oct 2019 09:11:23 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Kees Cook <keescook@...omium.org>
Cc:     Bill Metzenthen <billm@...bpc.org.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] x86: math-emu: check __copy_from_user result

On Wed, Oct 2, 2019 at 1:39 AM Kees Cook <keescook@...omium.org> 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