diff --git a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c index 862593f562..a4705bc7ce 100644 --- a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c +++ b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c @@ -845,10 +845,24 @@ InitializeDxeNxMemoryProtectionPolicy ( Attributes = GetPermissionAttributeForMemoryType (MemoryMapEntry->Type); if (Attributes != 0) { - SetUefiImageMemoryAttributes ( - MemoryMapEntry->PhysicalStart, - LShiftU64 (MemoryMapEntry->NumberOfPages, EFI_PAGE_SHIFT), - Attributes); + if (MemoryMapEntry->PhysicalStart == 0 && + PcdGet8 (PcdNullPointerDetectionPropertyMask) != 0) { + + ASSERT (MemoryMapEntry->NumberOfPages > 0); + // + // Skip page 0 if NULL pointer detection is enabled to avoid attributes + // overwritten. + // + SetUefiImageMemoryAttributes ( + MemoryMapEntry->PhysicalStart + EFI_PAGE_SIZE, + LShiftU64 (MemoryMapEntry->NumberOfPages - 1, EFI_PAGE_SHIFT), + Attributes); + } else { + SetUefiImageMemoryAttributes ( + MemoryMapEntry->PhysicalStart, + LShiftU64 (MemoryMapEntry->NumberOfPages, EFI_PAGE_SHIFT), + Attributes); + } } MemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize); }