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

[Jonathan Morton <chromatix99@gmail.com>]

Okay, it's a little bit more nuanced than I thought.  In fact there are *three* different CPU hardware vulnerabilities just disclosed.  I've summarised the impact in this Reddit post:

https://www.reddit.com/r/Amd/comments/7o2i91/technical_analysis_of_spectre_meltdown/

The TL;DR version is:

- Spectre v1 affects pretty much any modern out-of-order CPU, but is relatively low impact.  It could potentially be exploited using JIT compilation of untrusted eBPF or Javascript, but can only exfiltrate data from the local process.

- Spectre v2 affects most recent Intel CPUs and some recent, high-performance ARM CPU cores, but not AMD to any significant degree.  On vulnerable CPUs, it allows a local attacker to exfiltrate data from privileged address space.

- Meltdown is the nasty one which Linux kernel devs have been scrambling to mitigate.  So far, it is known to affect only Intel x86 CPUs, due to their unusually aggressive speculative behaviour regarding L1 cache hits.  On vulnerable CPUs, it allows a local attacker to exfiltrate data from privileged address space.

I don't think we need to worry about it too much in a router context.  Virtual server folks, OTOH...

 - Jonathan Morton