On Mon 2017-09-25 09:33:42, Ingo Molnar wrote:
> 
> * Pavel Machek <pavel@ucw.cz> wrote:
> 
> > > For example, there would be collision with regular user-space mappings, right? 
> > > Can local unprivileged users use mmap(MAP_FIXED) probing to figure out where 
> > > the kernel lives?
> > 
> > Local unpriviledged users can probably get your secret bits using cache probing 
> > and jump prediction buffers.
> > 
> > Yes, you don't want to leak the information using mmap(MAP_FIXED), but CPU will 
> > leak it for you, anyway.
> 
> Depends on the CPU I think, and CPU vendors are busy trying to mitigate this 
> angle.

I believe any x86 CPU running Linux will leak it. And with CPU vendors
putting "artifical inteligence" into branch prediction, no, I don't
think it is going to get better.

That does not mean we shoudl not prevent mmap() info leak, but...

									Pavel
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