Re: [MdeModulePkg] SetVirtualAddressMap() crashed due to DxeReportStatusCodeLib assuming the state of the BootService Memory at runtime.

["Kinney, Michael D" <michael.d.kinney@intel.com>]

Hi Andrew,

I am staring at the code.  Something is not right here, but I am 
concerned that there are use cases I am not considering yet.  Here
is my analysis so far.

Here are the lib instances I see: 
(ignoring IntelFramework ones for the purposes of this discussion).

MdeModulePkg\Library\DxeReportStatusCodeLib\DxeReportStatusCodeLib.inf(25):  
  LIBRARY_CLASS = ReportStatusCodeLib|DXE_CORE DXE_DRIVER DXE_RUNTIME_DRIVER DXE_SAL_DRIVER DXE_SMM_DRIVER UEFI_APPLICATION UEFI_DRIVER SMM_CORE

MdeModulePkg\Library\PeiReportStatusCodeLib\PeiReportStatusCodeLib.inf(27):
  LIBRARY_CLASS = ReportStatusCodeLib|SEC PEIM PEI_CORE

MdeModulePkg\Library\RuntimeDxeReportStatusCodeLib\RuntimeDxeReportStatusCodeLib.inf(23):
  LIBRARY_CLASS = ReportStatusCodeLib|DXE_RUNTIME_DRIVER DXE_SAL_DRIVER

MdeModulePkg\Library\SmmReportStatusCodeLib\SmmReportStatusCodeLib.inf(26):
  LIBRARY_CLASS = ReportStatusCodeLib|DXE_SMM_DRIVER SMM_CORE

MdePkg\Library\BaseReportStatusCodeLibNull\BaseReportStatusCodeLibNull.inf(23):
  LIBRARY_CLASS = ReportStatusCodeLib

* The BASE one that is a Null instance makes sense when disabling Report Status Code.
* The PEI one makes sense for its module compatibility.
* The SMM one also makes sense its module compatibility.
* And the RuntimeDxe one also makes sense its module compatibility.
* The DXE one seems to be over specified and if we reduced its module 
  compatibility, the SMM and RuntimeDxe lib instances can be used to cover 
  those module types.

When I look at the source code in DxeReportStatusCodeLib, I see comments
that describe the use case where a module is dispatched before the Report
Status Code Protocol is available.

The use case you are describing is when the first call to Report Status 
Code by a module occurs after ExitBootServices().  In that case, we 
depend on the Boot Services table being zeroed to exit early.

I agree that no component should depend on Boot Services table being 
cleared to zeros at ExitBootServices().  It is legal from UEFI/PI spec 
to not zero at all, or in your example, fill with a pattern other than
zeros.

It appears that the use case of first call to Report Status Code after
ExitBootServices() is not covered by the DXE lib instance, and we have
just been getting lucky due to zeroing behavior of boot services table.

I can think of a couple options:

* Update DXE INF to remove the DXE Runtime, DXE SAL, SMM, SMM Core module
  types.  This may break platform builds if a platform is using this lib
  mapping for modules of the types being removed.  However, those could
  be considered platform DSC bugs.

* Update DXE lib instance to add ExitBootServices() and SetVirtualAddressMap()
  events.  However, this would basically make the DXE lib instance the
  same as the DXE Runtime instance and would increase size of non-RT 
  components.

I would prefer the first option, but we would need to do some testing to
see how many platform DSC files break.

Mike

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Andrew Fish
> Sent: Tuesday, August 9, 2016 7:50 AM
> To: Zeng, Star <star.zeng@intel.com>
> Cc: edk2-devel <edk2-devel@lists.01.org>
> Subject: Re: [edk2] [MdeModulePkg] SetVirtualAddressMap() crashed due to
> DxeReportStatusCodeLib assuming the state of the BootService Memory at runtime.
> 
> 
> > On Aug 8, 2016, at 7:26 PM, Zeng, Star <star.zeng@intel.com> wrote:
> >
> > On 2016/8/9 10:07, Andrew Fish wrote:
> >>
> >>> On Aug 8, 2016, at 6:21 PM, Zeng, Star <star.zeng@intel.com> wrote:
> >>>
> >>> Andrew,
> >>>
> >>> Should MdeModulePkg/Library/RuntimeDxeReportStatusCodeLib be used for your case
> if there are really runtime status code reporting needed?
> >>>
> >>
> >> Star,
> >>
> >> If the Library instance does not fully support DXE_RUNTIME_DRIVER, why is it
> listed in the LIBRARY_CLASS as supported?
> >
> > This kind of library can support DXE_RUNTIME_DRIVER at boot time, for example
> UefiHiiLib, UefiHiiServicesLib, UefiBootServicesTableLib, DxePcdLib and etc.
> >
> 
> Star,
> 
> I understand giving access to Boot Services resources to a Runtime Driver for its
> constructor. I think the difference here is the DxeReportStatusCodeLib is abstracting
> a runtime service, but not doing it in a way to really works properly at runtime in
> all cases. I would expect that a library abstraction a runtime feature would work at
> runtime. Which is why I ended up with a "bad" mapping in the first place.
> 
> Thanks,
> 
> Andrew Fish
> 
> >>
> >>
> https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Library/DxeReportStatusCod
> eLib/DxeReportStatusCodeLib.inf#L25
> >>
> >> LIBRARY_CLASS                  = ReportStatusCodeLib|DXE_CORE DXE_DRIVER
> DXE_RUNTIME_DRIVER DXE_SAL_DRIVER DXE_SMM_DRIVER UEFI_APPLICATION UEFI_DRIVER
> SMM_CORE
> >>
> >> Actually I tried to add the UefiRuntimeDriverLib and the build failed as
> UefiRuntimeDriverLib was not supported for the DXE_CORE type. Maybe the bug is this
> library instance lists DXE_RUNTIME_DRIVER,  DXE_SAL_DRIVER and DXE_SMM_DRIVER when it
> has special case code to support DXE_CORE? Maybe this library is trying to do too
> many things?
> >>
> >> What ReportStatusCodeLib would you recommend to link with RuntimeDxe driver:
> https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/RuntimeDxe/RuntimeDxe
> .inf
> >
> > [LibraryClasses.common.DXE_CORE]
> >
> ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLi
> b.inf
> >
> > [LibraryClasses.common.DXE_RUNTIME_DRIVER]
> >
> ReportStatusCodeLib|MdeModulePkg/Library/RuntimeDxeReportStatusCodeLib/RuntimeDxeRepo
> rtStatusCodeLib.inf
> >
> > [LibraryClasses.common.UEFI_DRIVER]
> >
> ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLi
> b.inf
> >
> > [LibraryClasses.common.DXE_DRIVER]
> >
> ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLi
> b.inf
> >
> > [LibraryClasses.common.UEFI_APPLICATION]
> >
> ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLi
> b.inf
> >
> > Thanks,
> > Star
> >
> >>
> >> Thanks,
> >>
> >> Andrew Fish
> >>
> >>> Thanks,
> >>> Star
> >>> -----Original Message-----
> >>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Andrew
> Fish
> >>> Sent: Tuesday, August 9, 2016 7:08 AM
> >>> To: edk2-devel <edk2-devel@lists.01.org>
> >>> Subject: [edk2] [MdeModulePkg] SetVirtualAddressMap() crashed due to
> DxeReportStatusCodeLib assuming the state of the BootService Memory at runtime.
> >>>
> >>> I was messing about with an ExitBootServices test that fills boot services memory
> with 0xAFAFAFAFAFAFAFAF (It was Vincent's idea to use my Initials but it has the
> handy property of being a non-cononical address and causes on GP fault on X64) and
> SetVirtualAddressMap() started crashing.
> >>>
> >>> It looks like this code is assuming the 1st call to ReportStatus code will not
> happen at runtime. This is not the case for the RuntimeDxe driver.
> >>>
> https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Library/DxeReportStatusCod
> eLib/ReportStatusCodeLib.c#L43
> >>> VOID
> >>> InternalGetReportStatusCode (
> >>> VOID
> >>> )
> >>> {
> >>> EFI_STATUS  Status;
> >>>
> >>> if (mReportStatusCodeLibStatusCodeProtocol != NULL) {
> >>>  return;
> >>> }
> >>>
> >>> //
> >>> // Check gBS just in case ReportStatusCode is called before gBS is initialized.
> >>> //
> >>> if (gBS != NULL && gBS->LocateProtocol != NULL) {
> >>>  Status = gBS->LocateProtocol (&gEfiStatusCodeRuntimeProtocolGuid, NULL, (VOID**)
> &mReportStatusCodeLibStatusCodeProtocol);
> >>>  if (EFI_ERROR (Status)) {
> >>>    mReportStatusCodeLibStatusCodeProtocol = NULL;
> >>>  }
> >>> }
> >>> }
> >>>
> >>> I'm guessing this seems to work due
> to:https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Dxe/DxeMain/DxeMai
> n.c#L803
> >>>
> >>> //
> >>> // Zero out the Boot Service Table
> >>> //
> >>> ZeroMem (gBS, sizeof (EFI_BOOT_SERVICES));
> >>>
> >>>
> >>> Thus if I'm looking at this code correctly it only looks like it works at Runtime
> since it is depending on the value of a boot services memory buffer not changing.
> This is not a valid assumption as that code is owned by the caller of
> ExitBootServices, so it should be legal for my test to change the value.
> >>>
> >>> I wanted to get a few more eyes on this prior to filling a bug?
> >>>
> >>> Thanks,
> >>>
> >>> Andrew Fish
> >>>
> >>>
> >>> _______________________________________________
> >>> edk2-devel mailing list
> >>> edk2-devel@lists.01.org
> >>> https://lists.01.org/mailman/listinfo/edk2-devel
> >>> _______________________________________________
> >>> edk2-devel mailing list
> >>> edk2-devel@lists.01.org
> >>> https://lists.01.org/mailman/listinfo/edk2-devel
> >
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