C++: Fix false positive by recognizing more absolute value functions in Overflow.qll

Author: MathiasVP

cpp/ql/src/semmle/code/cpp/security/Overflow.qll

@@ -12,7 +12,7 @@ import semmle.code.cpp.rangeanalysis.RangeAnalysisUtils
  * Holds if the value of `use` is guarded using `abs`.
  */
 predicate guardedAbs(Operation e, Expr use) {
-  exists(FunctionCall fc | fc.getTarget().getName() = "abs" |
+  exists(FunctionCall fc | fc.getTarget().getName() = ["abs", "labs", "llabs", "imaxabs"] |
     fc.getArgument(0).getAChild*() = use and
     guardedLesser(e, fc)
   )

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

@@ -3,10 +3,6 @@
 | test5.cpp:17:6:17:18 | call to getTaintedInt | $@ 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 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 |
-| test5.cpp:30:17:30:23 | tainted | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
-| test5.cpp:30:17:30:23 | tainted | $@ flows to here and is used in arithmetic, potentially causing an underflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
-| test5.cpp:30:27:30:33 | tainted | $@ flows to here and is used in arithmetic, potentially causing an overflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
-| test5.cpp:30:27:30:33 | tainted | $@ 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/test5.cpp

@@ -27,6 +27,6 @@ void useTaintedIntWithGuard() {
 	int tainted = getTaintedInt();
 
 	if(imaxabs(tainted) <= 100) {
-		int product = tainted * tainted; // GOOD: can't underflow/overflow [FALSE POSITIVE]
+		int product = tainted * tainted; // GOOD: can't underflow/overflow
 	}
 }