linux-kernel - Re: [PATCH v2] x86/boot/64/clang: Use fixup_pointer() to access '__supported_pte

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] [day] [month] [year] [list]

Date:   Wed, 09 May 2018 09:16:03 +0000
From:   Alexander Potapenko <glider@...gle.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     dave.hansen@...ux.intel.com, Ingo Molnar <mingo@...nel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Dmitriy Vyukov <dvyukov@...gle.com>,
        Michael Davidson <md@...gle.com>
Subject: Re: [PATCH v2] x86/boot/64/clang: Use fixup_pointer() to access '__supported_pte_mask'

On Tue, May 8, 2018 at 11:44 PM Kirill A. Shutemov <
kirill.shutemov@...ux.intel.com> wrote:

> On Tue, May 08, 2018 at 04:28:29PM +0000, Alexander Potapenko wrote:
> > @@ -196,7 +204,8 @@ unsigned long __head __startup_64(unsigned long
physaddr,
> >
> >       pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
> >       /* Filter out unsupported __PAGE_KERNEL_* bits: */
> > -     pmd_entry &= __supported_pte_mask;
> > +     mask_ptr = (pteval_t *)fixup_pointer(&__supported_pte_mask,
physaddr);

> Do we really need the cast here?
Correct, we do not.

> --
>   Kirill A. Shutemov



-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg