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

[Haitao Huang]

On Fri, 03 Jul 2020 22:31:10 -0500, Jarkko Sakkinen  
<jarkko.sakki...@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