C++: Add testcases with false positives.

Author: MathiasVP

cpp/ql/test/query-tests/Security/CWE/CWE-119/semmle/tests/OverflowStatic.expected

@@ -5,6 +5,8 @@
 | tests.cpp:245:42:245:42 | 6 | Potential buffer-overflow: 'global_array_5' has size 5 not 6. |
 | tests.cpp:349:2:349:14 | access to array | Potential buffer-overflow: 'charArray' has size 10 but 'charArray[10]' is accessed here. |
 | tests.cpp:350:17:350:29 | access to array | Potential buffer-overflow: 'charArray' has size 10 but 'charArray[10]' is accessed here. |
+| tests.cpp:594:4:594:12 | access to array | Potential buffer-overflow: counter 'k' <= 100 but 'buffer' has 16 elements. |
+| tests.cpp:603:24:603:24 | n | Potential buffer-overflow: 'dest' has size 128 not 132. |
 | var_size_struct.cpp:54:5:54:14 | access to array | Potential buffer-overflow: 'str' has size 1 but 'str[1]' is accessed here. |
 | var_size_struct.cpp:55:5:55:14 | access to array | Potential buffer-overflow: 'str' has size 1 but 'str[1]' is accessed here. |
 | var_size_struct.cpp:103:39:103:41 | 129 | Potential buffer-overflow: 'str' has size 128 not 129. |

cpp/ql/test/query-tests/Security/CWE/CWE-119/semmle/tests/tests.cpp

@@ -586,6 +586,23 @@ void test21(bool cond)
 	if (ptr[-1] == 0) { return; } // GOOD: accesses buffer[1]
 }
 
+void test22(bool b, const char* source) {
+	char buffer[16];
+	int k;
+	for (k = 0; k <= 100; k++) {
+		if(k < 16) {
+			buffer[k] = 'x'; // GOOD [FALSE POSITIVE]
+		}
+	}
+
+	char dest[128];
+	int n = b ? 1024 : 132;
+	if (n >= 128) {
+    return;
+  }
+  memcpy(dest, source, n); // GOOD [FALSE POSITIVE]
+}
+
 int main(int argc, char *argv[])
 {
 	long long arr17[19];
@@ -609,6 +626,7 @@ int main(int argc, char *argv[])
 	test19(argc == 0);
 	test20();
 	test21(argc == 0);
+	test22(argc == 0, argv[0]);
 
 	return 0;
 }