From: Jonathan Morton <chromatix99@gmail.com>
To: "dpreed@deepplum.com" <dpreed@deepplum.com>
Cc: Dave Taht <dave.taht@gmail.com>, cerowrt-devel@lists.bufferbloat.net
Subject: Re: [Cerowrt-devel] KASLR: Do we have to worry about other arches than x86?
Date: Thu, 4 Jan 2018 23:20:45 +0200 [thread overview]
Message-ID: <FBCE3AD8-4799-400B-81A3-CB787581E80A@gmail.com> (raw)
In-Reply-To: <1515097734.30384822@apps.rackspace.com>
> On 4 Jan, 2018, at 10:28 pm, dpreed@deepplum.com wrote:
>
> 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.
...on Intel CPUs since Nehalem and Silvermont, and on a very small number of ARM's highest-performance cores (which you're unlikely to find in CPE).
But not on most ARM cores, nor on AMD CPUs. These all do their security checks more promptly, so the rogue data never reaches either a shadow register nor an execution unit, even under speculative execution.
The conceptually simplest mitigation turns out to be switching off branch prediction.
- Jonathan Morton
next prev parent reply other threads:[~2018-01-04 21:20 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-01 23:08 Dave Taht
[not found] ` <CAJq5cE23bbiPE0a_9zd1VLnO7=c7bjmwwxVwaD2=to3fg5TOjA@mail.gmail.com>
2018-01-01 23:27 ` Jonathan Morton
2018-01-02 19:06 ` Jonathan Morton
2018-01-04 12:09 ` Jonathan Morton
2018-01-04 13:38 ` Dave Taht
2018-01-04 13:48 ` Jonathan Morton
2018-01-04 13:59 ` Dave Taht
2018-01-04 14:49 ` Jonathan Morton
2018-01-04 14:53 ` Dave Taht
2018-01-04 20:28 ` dpreed
2018-01-04 21:20 ` Jonathan Morton [this message]
2018-01-04 21:40 ` Dave Taht
2018-01-04 21:51 ` valdis.kletnieks
2018-01-04 21:44 ` Joel Wirāmu Pauling
2018-01-04 21:47 ` Dave Taht
2018-01-04 21:52 ` Joel Wirāmu Pauling
2018-01-04 21:54 ` Dave Taht
2018-01-04 21:57 ` Joel Wirāmu Pauling
[not found] ` <1515103187.670416570@apps.rackspace.com>
2018-01-04 22:02 ` Joel Wirāmu Pauling
[not found] ` <1515103048.715224709@apps.rackspace.com>
2018-01-04 22:00 ` Joel Wirāmu Pauling
2018-01-04 22:09 ` dpreed
2018-01-04 22:13 ` Joel Wirāmu Pauling
2018-01-04 22:15 ` Dave Taht
2018-01-04 22:26 ` Jonathan Morton
2018-01-04 22:35 ` Joel Wirāmu Pauling
2018-01-04 22:58 ` [Cerowrt-devel] Spectre and EBPF JIT dpreed
2018-01-05 4:53 ` Dave Taht
2018-01-05 14:07 ` Jonathan Morton
2018-01-05 15:35 ` dpreed
2018-01-05 19:18 ` Jonathan Morton
2018-01-05 20:15 ` David Lang
2018-01-04 22:02 [Cerowrt-devel] KASLR: Do we have to worry about other arches than x86? dpreed
2018-01-04 22:02 dpreed
2018-01-04 22:04 ` Dave Taht
2018-01-04 22:12 ` dpreed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://lists.bufferbloat.net/postorius/lists/cerowrt-devel.lists.bufferbloat.net/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=FBCE3AD8-4799-400B-81A3-CB787581E80A@gmail.com \
--to=chromatix99@gmail.com \
--cc=cerowrt-devel@lists.bufferbloat.net \
--cc=dave.taht@gmail.com \
--cc=dpreed@deepplum.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox