linux-kernel - Re: [PATCH 5/8] x86/head: remove useless zeroed word

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 for Android: free password hash cracker in your pocket

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

Message-ID: <87y43ozd8h.fsf@tassilo.jf.intel.com>
Date:   Mon, 22 Aug 2016 14:48:46 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...capital.net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Byungchul Park <byungchul.park@....com>,
        Nilay Vaish <nilayvaish@...il.com>
Subject: Re: [PATCH 5/8] x86/head: remove useless zeroed word

Josh Poimboeuf <jpoimboe@...hat.com> writes:

> This zeroed word has no apparent purpose, so remove it.
>
> Brian Gerst says:
>
>   "FYI the word used to be the SS segment selector for the LSS
>   instruction, which isn't needed in 64-bit mode."
>

Seems dangerous. It wouldn't surprise me if some CPUs or x86 emulations
load it anyways and trigger page faults if there is really nothing
there.

-Andi