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

[Ard Biesheuvel]

On Mon, 13 Dec 2021 at 19:23, Kun Qin <kuqin12 at gmail.com> wrote:
>
> 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?
>

My apologies for not responding to these changes.

If these patches are still relevant, please rebase and resend them.


> On 12/06/2021 10:41, Ard Biesheuvel wrote:
> > On Mon, 6 Dec 2021 at 19:35, Kun Qin <kuqin12 at 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 at intel.com>
> >>> Cc: Liming Gao <gaoliming at byosoft.com.cn>
> >>> Cc: Hao A Wu <hao.a.wu at intel.com>
> >>> Cc: Leif Lindholm <leif at nuviainc.com>
> >>> Cc: Ard Biesheuvel <ardb+tianocore at kernel.org>
> >>> Cc: Bret Barkelew <Bret.Barkelew at microsoft.com>
> >>> Cc: Michael Kubacki <michael.kubacki at 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(-)
> >>>


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