Fix #964 (Integer division by zero exception)

http://sourceforge.net/apps/trac/cppcheck/ticket/964

lib/checkbufferoverrun.cpp

@@ -678,6 +678,8 @@ void CheckBufferOverrun::checkGlobalAndLocalVariable()
                 // malloc() gets count of bytes and not count of
                 // elements, so we should calculate count of elements
                 // manually
+                unsigned int sizeOfType = _tokenizer->sizeOfType(declTok);
+                if (sizeOfType > 0)
                     size /= _tokenizer->sizeOfType(declTok);
             }
         }

test/testbufferoverrun.cpp

@@ -134,6 +134,7 @@ private:
         TEST_CASE(memset1);
         TEST_CASE(counter_test);
         TEST_CASE(strncpy1);
+        TEST_CASE(unknownType);
     }
 
 
@@ -1335,6 +1336,15 @@ private:
               "}\n");
         ASSERT_EQUALS("[test.cpp:4]: (error) Buffer access out-of-bounds\n", errout.str());
     }
+
+    void unknownType()
+    {
+        check("void f()\n"
+              "{\n"
+              " UnknownType *a = malloc(4);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
 };
 
 REGISTER_TEST(TestBufferOverrun)