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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;
  }

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
This commit is contained in:
Hao Wu 2017-03-22 10:08:55 +08:00
parent 89558f1653
commit 1860cb00c1
1 changed files with 5 additions and 0 deletions
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5
MdeModulePkg/Core/Dxe/Misc/PropertiesTable.c
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@ -576,6 +576,11 @@ SplitRecord (
TempRecord.NumberOfPages = EfiSizeToPages (PhysicalEnd - PhysicalStart); TempRecord.NumberOfPages = EfiSizeToPages (PhysicalEnd - PhysicalStart);
} while ((ImageRecord != NULL) && (PhysicalStart < PhysicalEnd)); } 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; return TotalNewRecordCount - 1;
} }