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

[Daniel Gruss]

On 2017-05-05 17:53, Jann Horn wrote:
> Ah, I think I understand. The kernel stacks are mapped, but
> cpu_current_top_of_stack isn't, so you can't find the stack until after the CR3
> switch in the syscall handler?

That's the idea. Only the absolute minimum that is required for a 
context switch remains mapped (+ it is mapped at an offset which does 
not depend on KASLR -> we do not leak the KASLR offsets).