Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver

Haitao Huang
2020-09-02T03:07:02Z

On Fri, 03 Jul 2020 22:31:10 -0500, Jarkko Sakkinen
<jarkko.sakkinen@linux.intel.com> wrote:

> On Wed, Jul 01, 2020 at 08:59:02PM -0700, Sean Christopherson wrote:
>> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
>> > +static int sgx_validate_secs(const struct sgx_secs *secs,
>> > + unsigned long ssaframesize)
>> > +{
>> > + if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
>> > + return -EINVAL;
>> > +
>> > + if (secs->base & (secs->size - 1))
>> > + return -EINVAL;
>> > +
>> > + if (secs->miscselect & sgx_misc_reserved_mask ||
>> > + secs->attributes & sgx_attributes_reserved_mask ||
>> > + secs->xfrm & sgx_xfrm_reserved_mask)
>> > + return -EINVAL;
>> > +
>> > + if (secs->attributes & SGX_ATTR_MODE64BIT) {
>> > + if (secs->size > sgx_encl_size_max_64)
>> > + return -EINVAL;
>> > + } else if (secs->size > sgx_encl_size_max_32)
>> > + return -EINVAL;
>>
>> These should be >=, not >, the SDM uses one of those fancy ≥ ligatures.
>>
>> Internal versions use more obvious pseudocode, e.g.:
>>
>> if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
>> (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
>> {
>> #GP(0);
>
> Updated as:
>
> static int sgx_validate_secs(const struct sgx_secs *secs)
> {
> u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ?
> sgx_encl_size_max_64 : sgx_encl_size_max_32;
>
> if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> return -EINVAL;
>
> if (secs->base & (secs->size - 1))
> return -EINVAL;
>
> if (secs->miscselect & sgx_misc_reserved_mask ||
> secs->attributes & sgx_attributes_reserved_mask ||
> secs->xfrm & sgx_xfrm_reserved_mask)
> return -EINVAL;
>
> if (secs->size >= max_size)
> return -EINVAL;
>

This should be > not >=. Issue raised and fixed by Fábio Silva for ported
patches for OOT SGX support:
https://github.com/intel/SGXDataCenterAttestationPrimitives/pull/123

I tested and verified with Intel arch, the comparison indeed should be >.

Thanks
Haitao