Re: [PATCH 05/11] x86/fpu: set PKRU state for kernel threads

[Andy Lutomirski]

> On Oct 18, 2018, at 2:24 PM, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:
> 
> On 2018-10-18 13:56:24 [-0700], Dave Hansen wrote:
>>> But this is not the only loophole: There is ptrace interface which is
>>> used by gdb (just checked) and also bypasses PKRU. Soâ
>> 
>> Bypassing protection keys is not a big deal IMNHO.  In places where a
>> sane one is not readily available, I'm totally fine with just
>> effectively disabling it (PKRU=0) for the length of time it isn't available.
> 
> Okay, this makes things easier. Let document that for kernel threads we
> use PKRU=0. This should be happening in my try right now. I double check
> tomorrow just in caseâ
> 
> 

If you document that, please at least document that itâs a bug and not intended behavior.