Reviewed-by: jiewen@intel.com
> -Original Message-
> From: Wu, Hao A
> Sent: Monday, April 10, 2017 2:16 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A ; Yao, Jiewen
> Subject: [PATCH] MdeModulePkg/DxeCore: Add ASSERT to ensure no subtract
> underflow
>
> For function SplitRecord() in file PropertiesTable.c, there is a
> potential subtract underflow case for line:
>
> return TotalNewRecordCount - 1;
>
> However, such case will not happen since the logic in function
> SplitTable() ensure that when calling SplitRecord(), the variable
> 'TotalNewRecordCount' will not be zero when performing the subtraction.
> It will be handled in the previous if statement:
>
> if (MaxSplitRecordCount == 0) {
> CopyMem (NewRecord, OldRecord, DescriptorSize);
> return 0;
> }
>
> Cc: Jiewen Yao
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Hao Wu
> ---
> MdeModulePkg/Core/Dxe/Misc/PropertiesTable.c | 5 +
> 1 file changed, 5 insertions(+)
>
> diff --git a/MdeModulePkg/Core/Dxe/Misc/PropertiesTable.c
> b/MdeModulePkg/Core/Dxe/Misc/PropertiesTable.c
> index e7c4a95712..6cf5edcbe5 100644
> --- a/MdeModulePkg/Core/Dxe/Misc/PropertiesTable.c
> +++ b/MdeModulePkg/Core/Dxe/Misc/PropertiesTable.c
> @@ -576,6 +576,11 @@ SplitRecord (
> TempRecord.NumberOfPages = EfiSizeToPages (PhysicalEnd -
> PhysicalStart);
>} while ((ImageRecord != NULL) && (PhysicalStart < PhysicalEnd));
>
> + //
> + // The logic in function SplitTable() ensures that TotalNewRecordCount will
> not be zero if the
> + // code reaches here.
> + //
> + ASSERT (TotalNewRecordCount != 0);
>return TotalNewRecordCount - 1;
> }
>
> --
> 2.12.0.windows.1
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