From 1860cb00c18c6f0c58336ea15a63889dabd31d15 Mon Sep 17 00:00:00 2001 From: Hao Wu Date: Wed, 22 Mar 2017 10:08:55 +0800 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; } Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Hao Wu Reviewed-by: Jiewen Yao --- 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; } -- 2.39.2