Re: [edk2-devel] [PATCH v1 0/2] MM communicate functionality in variable policy

["Kun Qin" <kuqin12@gmail.com>]

Hi ArmPkg and MdeModulePkg maintainers,

Now that the hard freeze is lifted, could you please provide some 
feedback on these patches when you have a chance?

Thanks in advance.

Regards,
Kun

On 12/06/2021 10:41, Ard Biesheuvel wrote:
> On Mon, 6 Dec 2021 at 19:35, Kun Qin <kuqin12@gmail.com> wrote:
>>
>> Hi ArmPkg and MdeModulePkg maintainers,
>>
>> It has been a week since the patches were sent. Could you please review
>> the changes and let me know if there is any feedback? Any input is
>> appreciated.
>>
> 
> As far as I know, we are still in hard freeze for the upcoming stable tag.
> 
>>
>> On 11/29/2021 16:39, Kun Qin via groups.io wrote:
>>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3709
>>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3751
>>>
>>> Currently, setups with variable policy operations used together with MM
>>> communicate from ArmPkg could fail with `EFI_INVALID_PARAMETER`. This was
>>> due to the errors from 2 following aspects:
>>>
>>> 1. For variable policy implementations in MdeModulePkg, the DXE runtime
>>> agent would communicate to MM to disable, register or query policies.
>>> However, during these operations, the MessageLength calculation is
>>> including MM communicate header. This could lead to MM agent read data
>>> across the given buffer boundary and/or trigger other errors.
>>>
>>> 2. On the other hand, current MM communicate routine from ArmPkg would
>>> fail the function if the input message length does not equal to input
>>> buffer size.
>>>
>>> As defined in PI specification, the `CommSize`, when as input, should
>>> stand for "The size of the data buffer being passed in", which would mean
>>> the maximal number of bytes `CommBuffer` can hold. In turn, the value of
>>> this input parameter can be used for MM handlers to determine whether the
>>> output data is too large to fit in this buffer. Enforcing the incoming
>>> buffer to hold exactly the number of used bytes mismatches with the PI
>>> spec description.
>>>
>>> This change fix MessageLength field calculation from variable policy and
>>> updated input argument inspections from MM communicate routine in ArmPkg
>>> to match PI spec descriptions.
>>>
>>> Patch v1 branch: https://github.com/kuqin12/edk2/tree/mm_communicate_check
>>>
>>> Cc: Jian J Wang <jian.j.wang@intel.com>
>>> Cc: Liming Gao <gaoliming@byosoft.com.cn>
>>> Cc: Hao A Wu <hao.a.wu@intel.com>
>>> Cc: Leif Lindholm <leif@nuviainc.com>
>>> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
>>> Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
>>> Cc: Michael Kubacki <michael.kubacki@microsoft.com>
>>>
>>> Kun Qin (2):
>>>     MdeModulePkg: VariableSmmRuntimeDxe: Fix Variable Policy Message
>>>       Length
>>>     ArmPkg: MmCommunicationDxe: Update MM communicate input arguments
>>>       checks
>>>
>>>    ArmPkg/Drivers/MmCommunicationDxe/MmCommunication.c               | 44 ++++++++++++--------
>>>    MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c | 10 ++---
>>>    2 files changed, 32 insertions(+), 22 deletions(-)
>>>