Re: [PATCH] UefiCpuPkg/CpuDxe: fix SetMemoryAttributes issue in 32-bit mode

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

On 1/16/2018 10:47 AM, Jian J Wang wrote:
> In 32-bit mode, the BIOS will not create page table for memory beyond
> 4GB and therefore it cannot handle the attributes change request for
> those memory. But current CpuDxe doesn't check this situation and still
> try to complete the request, which will cause attributes of incorrect
> memory address to be changed due to type cast from 64-bit to 32-bit.
> 
> This patch fixes this issue by checking the end address of input
> memory block and returning EFI_UNSUPPORTED if it's out of range.
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> ---
>   UefiCpuPkg/CpuDxe/CpuPageTable.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/UefiCpuPkg/CpuDxe/CpuPageTable.c b/UefiCpuPkg/CpuDxe/CpuPageTable.c
> index a9c9bc9d5e..3ad55f65c5 100644
> --- a/UefiCpuPkg/CpuDxe/CpuPageTable.c
> +++ b/UefiCpuPkg/CpuDxe/CpuPageTable.c
> @@ -699,6 +699,10 @@ ConvertMemoryPageAttributes (
>         DEBUG ((DEBUG_ERROR, "Non-PAE Paging!\n"));
>         return EFI_UNSUPPORTED;
>       }
> +    if ((BaseAddress + Length) > BASE_4GB) {
> +      DEBUG ((DEBUG_ERROR, "Beyond 4GB memory in 32-bit mode!\n"));
> +      return EFI_UNSUPPORTED;
> +    }
>       break;
>     case IMAGE_FILE_MACHINE_X64:
>       ASSERT (CurrentPagingContext.ContextData.X64.PageTableBase != 0);
> 

Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
-- 
Thanks,
Ray