Re: Restricting rdtsc [was: kernel aslr]

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Tue, Mar 28, 2017 at 04:58:58PM +0200, Maxime Villard wrote:
> Having read several papers on the exploitation of cache latency to defeat
> aslr (kernel or not), it appears that disabling the rdtsc instruction is a
> good mitigation on x86. However, some applications can legitimately use it,
> so I would rather suggest restricting it to root instead.

This will break a ton of stuff.  Code all over the place checks if it's
on x86 and uses rdtsc when it wants a quick timestamp.

Thor