CPP: Add a test using strtoul in a taint query.

Author: geoffw0

cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/tainted/ArithmeticTainted.expected

@@ -1,6 +1,8 @@
 | test3.c:15:10:15:10 | x | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test3.c:11:15:11:18 | argv | User-provided value |
 | test3.c:15:14:15:14 | y | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test3.c:11:15:11:18 | argv | User-provided value |
 | test3.c:15:18:15:18 | z | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test3.c:11:15:11:18 | argv | User-provided value |
+| test5.cpp:19:6:19:6 | y | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
+| test5.cpp:19:6:19:6 | y | $@ flows to here and is used in arithmetic, potentially causing an underflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
 | test.c:14:15:14:28 | maxConnections | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test.c:11:29:11:32 | argv | User-provided value |
 | test.c:14:15:14:28 | maxConnections | $@ flows to here and is used in arithmetic, potentially causing an underflow. | test.c:11:29:11:32 | argv | User-provided value |
 | test.c:44:7:44:10 | len2 | $@ flows to here and is used in arithmetic, potentially causing an underflow. | test.c:41:17:41:20 | argv | User-provided value |

cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/tainted/IntegerOverflowTainted.expected

@@ -1,3 +1,4 @@
 | test3.c:12:31:12:34 | * ... | $@ flows to here and is used in an expression which might overflow negatively. | test3.c:11:15:11:18 | argv | User-provided value |
 | test3.c:13:16:13:19 | * ... | $@ flows to here and is used in an expression which might overflow negatively. | test3.c:11:15:11:18 | argv | User-provided value |
 | test4.cpp:13:17:13:20 | access to array | $@ flows to here and is used in an expression which might overflow negatively. | test4.cpp:9:13:9:16 | argv | User-provided value |
+| test5.cpp:10:9:10:15 | call to strtoul | $@ flows to here and is used in an expression which might overflow. | test5.cpp:9:7:9:9 | buf | User-provided value |

cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/tainted/test5.cpp

@@ -0,0 +1,20 @@
+
+char *gets(char *s);
+unsigned long int strtoul( const char * nptr, char ** endptr, int base);
+
+int getTaintedInt()
+{
+	char buf[128];
+
+	gets(buf);
+	return strtoul(buf, 0, 10);
+}
+
+void useTaintedInt()
+{
+	int x, y;
+
+	x = getTaintedInt() * 1024; // BAD: arithmetic on a tainted value [NOT DETECTED]
+	y = getTaintedInt();
+	y = y * 1024; // BAD: arithmetic on a tainted value
+}