CXX.FUNC.T2OLE.LOOP

Do not call T2OLE or OLE2CT within a loop.

The T2OLE and OLE2CT macros make use of the alloca method, which when used in a loop can overflow the stack.

Vulnerability and risk

T2OLE and OLE2CT require stack memory allocation (specifically the alloca method in A2W). Using these macros in a loop (especially depending on the length of the string) could increase the probability of a stack overflow.

Mitigation and prevention

By placing the macro in a separate fuction and calling the function in the loop instead of the macro. Then, the allocated memory on the stack is freed each time the function returns.

Example

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for(int cnt = 0; cnt < 100000; cnt++)
 {
  T2OLE(sArea);
  ptr->PutStringProperty(T2OLE(_T("DATA10")));
}

The stack space consumed is 100000 times the total allocated ineach loop, which is a wide char for each character in each string added together. i.e. Lots!