Re: [kernel-hardening] [RFC, PATCH] x86_64: KAISER - do not map kernel in user mode

[Daniel Gruss]

On 08.05.2017 16:09, Thomas Garnier wrote:
> > Just to correct my answer here as well: Although we experimented with fixed
> > mappings for per-cpu addresses, the current patch does not incorporate this
> > yet, so it indeed still leaks. However, it is not a severe problem. The
> > mapping of the required (per-cpu) variables would be at a fixed location in
> > the user CR3, instead of the ones that are used in the kernel.
>
> Why do you think it should be at a fixed location in the user CR3? I
> see that you just mirror the entries. You also mirror
> __entry_text_start / __entry_text_end which is part of the binary so
> will leak the base address of the kernel. Maybe I am missing
> something.

As I said, the current patch does not incorporate this yet, so yes, this part currently still leaks because we did not 
implement it yet.