Re: [PATCH v2 0/2] Resolve feature conflict between NX and Stack guard

["Ni, Ruiyu" <ruiyu.ni@Intel.com>]

On 3/6/2018 9:33 PM, Hao Wu wrote:
> V2 changes:
> 
> A. Use Hoblib APIs to get the base of stack from Hob.
> B. Remove unnecessary local variable used in function
>     InitializeDxeNxMemoryProtectionPolicy().
> 
> V1 history:
> 
> If enabled, NX memory protection feature will mark some types of active
> memory as NX (non-executable), which includes the first page of the stack.
> This will overwrite the attributes of the first page of the stack if the
> stack guard feature is also enabled.
> 
> The series will override the attributes setting to the first page of the
> stack by adding back the 'EFI_MEMORY_RP' attribute when the stack guard
> feature is enabled.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> 
> Hao Wu (2):
>    MdeModulePkg/Core: Refine handling NULL detection in NX setting
>    MdeModulePkg/Core: Fix feature conflict between NX and Stack guard
> 
>   MdeModulePkg/Core/Dxe/DxeMain.inf             |  4 +-
>   MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c | 74 +++++++++++++++++++++++----
>   2 files changed, 67 insertions(+), 11 deletions(-)
> 

       if (MemoryMapEntry->PhysicalStart == 0 &&
           PcdGet8 (PcdNullPointerDetectionPropertyMask) != 0) {

         ASSERT (MemoryMapEntry->NumberOfPages > 0);
         //
         // Add EFI_MEMORY_RP attribute for page 0 if NULL pointer 
detection is
         // enabled.
         //
[Ray] 1. I prefer to move the above comments before the "if (...)".

         SetUefiImageMemoryAttributes (
           0,
           EFI_PAGES_TO_SIZE (1),
           EFI_MEMORY_RP | Attributes);
       }

       if (StackBase != 0 &&
           (StackBase >= MemoryMapEntry->PhysicalStart &&
            StackBase <  MemoryMapEntry->PhysicalStart +
                         LShiftU64 (MemoryMapEntry->NumberOfPages, 
EFI_PAGE_SHIFT)) &&
           PcdGetBool (PcdCpuStackGuard)) {

         //
         // Add EFI_MEMORY_RP attribute for the first page of the stack 
if stack
         // guard is enabled.
         //
         SetUefiImageMemoryAttributes (
           StackBase,
           EFI_PAGES_TO_SIZE (1),
           EFI_MEMORY_RP | Attributes);
[Ray] 2. The StackBase is directly used here. So do we need to check
whether it's page aligned? Do we need to check whether the range
[StackBase, StackBase + 4KB) is inside the MemoryMapEntry?
       }

-- 
Thanks,
Ray