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

["Ard Biesheuvel" <ardb@kernel.org>]

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(-)
> >