linux-kernel - Re: [PATCH] x86/msr: do not warn on writes to OC

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: <CAHmME9rMbuXfR+eNhopX8FyeXerUrPo4vaWpF6Dx-u3NnTmrVg@mail.gmail.com>
Date:   Tue, 8 Sep 2020 21:07:20 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        kitsunyan <kitsunyan@...mail.cc>,
        "Brown, Len" <len.brown@...el.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sultan Alsawaf <sultan@...neltoast.com>
Subject: Re: [PATCH] x86/msr: do not warn on writes to OC_MAILBOX

On Tue, Sep 8, 2020 at 8:01 PM Borislav Petkov <bp@...en8.de> wrote:
>
> On Tue, Sep 08, 2020 at 07:42:12PM +0200, Jason A. Donenfeld wrote:
> > Are you prepared to track down all the MSRs that might maybe do
> > something naughty?
>
> I'm not prepared - that's why this MSR filtering. To block *all* direct
> MSR accesses from userspace in the future.
>
> > Does `dd` warn when you run `dd if=/dev/zero of=/dev/sda`?
>
> Yah, because that's the same as bricking your hardware. Geez.

Nobody is talking about bricking any hardware. Sorry if I seemed to
imply that before. In my experience, undervolting improperly results
in the CPU calculating things wrong and eventually crashing, and
overclocking usually will trip some thermal limits where the CPU
powers down. I've never experienced bricked hardware as a result of
this.

Jason