Re: [PATCH v3 03/25] x86/sgx: Wipe out EREMOVE from sgx_free_epc_page()

Paolo Bonzini
2021-03-23T17:07:08Z

On 23/03/21 18:02, Sean Christopherson wrote:
>> That's important, but it's even more important *to developers* that the
>> commit message spells out why this would be a kernel bug more often than
>> not. I for one do not understand it, and I suspect I'm not alone.
>>
>> Maybe (optimistically) once we see that explanation we decide that the
>> documentation is not important. Sean, Kai, can you explain it?
>
> Thought of a good analogy that can be used for the changelog and/or docs:
>
> This is effectively a kernel use-after-free of EPC, and due to the way SGX works,
> the bug is detected at freeing. Rather than add the page back to the pool of
> available EPC, the kernel intentionally leaks the page to avoid additional
> errors in the future.
>
> Does that help?

Very much, and for me this also settles the question of documentation.
Borislav or Kai, can you add it to the commit message?

Paolo