Add safety on generic param count

Author: josesimoes

src/CLR/Core/Execution.cpp

@@ -1979,6 +1979,13 @@ HRESULT CLR_RT_ExecutionEngine::InitializeLocals(
                     parser.Initialize_MethodLocals(assembly, methodDef);
                     CLR_RT_SignatureParser::Element element;
 
+                     // ensure we don’t walk past the available generic parameters
+                    const int maxParams = parser.GenParamCount;
+                    if (genericParamPosition < 0 || genericParamPosition >= maxParams)
+                    {
+                        NANOCLR_SET_AND_LEAVE(CLR_E_OUT_OF_RANGE);
+                    }
+
                     // advance into the VAR entry
                     parser.Advance(element);