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Add guard word before local var CMiniColDef[9] #73736

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Add guard word before local var CMiniColDef[9] #73736

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Add guard word before local var CMiniColDef[9]
RobertHenry6bev Aug 11, 2022
cccde5b
Simpolify asan-safe implementation of CMiniMdBasse:;InitColsForTable
RobertHenry6bev Aug 12, 2022
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16 changes: 12 additions & 4 deletions src/coreclr/md/runtime/metamodel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -717,7 +717,17 @@ CMiniMdBase::InitColsForTable(
// should we write the data into the structure
{
const CMiniTableDef *pTemplate; // Template table definition.
CMiniColDef pCols[9]; // The col defs to init.
const int MaxCols = 9;
typedef uint32_t markword_t;
BYTE tempCols[sizeof(markword_t) + MaxCols * sizeof(CMiniColDef)]; // keep aligned
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We use a single-byte marker everywhere in this code. I see no reason to use four bytes just at this particular place. This array contains 3-byte structures, so you cannot align them.

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Here is similar code in another function:

runtime/src/coreclr/md/enc/metamodelrw.cpp

Lines 3635 to 3638 in 2201016

// Mark the array of columns as not allocated (not ALLOCATED_MEMORY_MARKER) for SetNewColumnDefinition
// call bellow (code:#SetNewColumnDefinition_call)
*(BYTE *)(qbTempCols.Ptr()) = 0;
sTempTable.m_pColDefs = (CMiniColDef *)((BYTE *)(qbTempCols.Ptr()) + 1);

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And here:

runtime/src/coreclr/md/runtime/metamodel.cpp

Lines 880 to 889 in 4710133

BYTE *newMemory = new (nothrow) BYTE[(sizeof(CMiniColDef)*pTable->m_cCols)+1];
if (newMemory == NULL)
return E_OUTOFMEMORY;
// Mark the first byte in this as with the "allocated memory marker"
*newMemory = ALLOCATED_MEMORY_MARKER;
// Have the pointer point to the first Column Descriptor
pTable->m_pColDefs = BYTEARRAY_TO_COLDES(newMemory);


_ASSERTE(MaxCols >= pTable->m_cCols);
//
// Mark the array of columns as not allocated (eg, not ALLOCATED_MEMORY_MARKER)
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E.g. means “for example”. Did you actually mean "i.e."?

// for SetNewColumnDefinition call
//
memset(tempCols, 0, sizeof(markword_t));
CMiniColDef *pCols = BYTEARRAY_TO_COLDES(tempCols + sizeof(markword_t) - 1); // The col defs to init.
BYTE iOffset; // Running size of a record.
BYTE iSize; // Size of a field.
HRESULT hr = S_OK;
Expand All @@ -726,10 +736,8 @@ CMiniMdBase::InitColsForTable(
_ASSERTE(ARRAY_SIZE(pCols) >= pTable->m_cCols);

bExtra = 0;//<TODO>@FUTURE: save in schema header. until then use 0.</TODO>

iOffset = 0;

pTemplate = GetTableDefTemplate(ixTbl);
pTemplate = GetTableDefTemplate(ixTbl);

PREFIX_ASSUME(pTemplate->m_pColDefs != NULL);

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