[Cerowrt-devel] KASLR: Do we have to worry about other arches than x86?

Dave Taht dave.taht at gmail.com
Thu Jan 4 16:40:28 EST 2018

On Thu, Jan 4, 2018 at 12:28 PM, dpreed at deepplum.com
<dpreed at deepplum.com> wrote:
> Depending on how you set up your "home router", you might allow "infected"
> or "trojan" programs to run in userspace there. I wouldn't do that, because
> hardware is cheap. But some people like to throw all kinds of server code
> into their router setups - even stuff like node.js servers.

I do not know if lua-jit is used in lede or openwrt these days, but
since so far as I recall the web server runs as root anyway, once you
have any control of that you are nearly home free in the first place.

> The really core issue with Meltdown at the highest level is that the kernel
> is addressable from userspace, except for the "privilege level" in the page
> table entries. That's a couple of bits between userspace and data that
> userspace isn't supposed to ever see. And those bits are ignored during
> specutlative execution's memory accesses.

It is really bad news for cloudy multi-tenant devices, but to a huge
extent that market can more rapidly adapt than anywhere else.

A fear is that millions of formerly high end and insecure chips are in
the pipeline and that they will get dumped into any market that will
take them, which certainly includes IoT. It's hard to imagine
shipments of any of 'em actually stopping for any reason, or being
dumped in the ocean on entrance to the country, like some form of
TwEAk party.

And despite the patches ongoing, it's not clear to me if the door can
ever be completely shut on this past generation of hardware still
deployed, I'm still looking over the interrupt related portions and
scratching my head. Significantly limit, yes, close, no.

I guess I'm hoping for simple patches to the microcode to arrive next
week, even simply stuff to disable the branch predictor or speculative
execution, something simple, slow, and sane.

> -----Original Message-----
> From: "Dave Taht" <dave.taht at gmail.com>
> Sent: Thursday, January 4, 2018 9:53am
> To: "Jonathan Morton" <chromatix99 at gmail.com>
> Cc: cerowrt-devel at lists.bufferbloat.net
> Subject: Re: [Cerowrt-devel] KASLR: Do we have to worry about other arches
> than x86?
> On Thu, Jan 4, 2018 at 6:49 AM, Jonathan Morton <chromatix99 at gmail.com>
> wrote:
>>> On 4 Jan, 2018, at 3:59 pm, Dave Taht <dave.taht at gmail.com> wrote:
>>> Alan cox has been doing a good job of finding the good stuff. Power
>>> and the IBM z-series are also affected.
>> Conversely, the ARM-1176, Cortex-A7 and Cortex-A53 cores used by various
>> iterations of the Raspberry Pi are not affected. These are all in-order
>> execution CPUs with short pipelines, and I think they're representative of
>> what you'd want in CPE.
> Well, I'd hope that this string of bugs stalls deployment of more
> advanced arches in this space until the speculative execution bugs are
> fully resolved.
> (and I *vastly* prefer short pipelines)
>> - Jonathan Morton
> --
> Dave Täht
> CEO, TekLibre, LLC
> http://www.teklibre.com
> Tel: 1-669-226-2619
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Dave Täht
CEO, TekLibre, LLC
Tel: 1-669-226-2619

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