1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
//== DivZeroChecker.cpp - Division by zero checker --------------*- C++ -*--==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This defines DivZeroChecker, a builtin check in ExprEngine that performs
// checks for division by zeros.
//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
using namespace clang;
using namespace ento;
namespace {
class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
mutable OwningPtr<BuiltinBug> BT;
void reportBug(const char *Msg,
ProgramStateRef StateZero,
CheckerContext &C) const ;
public:
void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
};
} // end anonymous namespace
void DivZeroChecker::reportBug(const char *Msg,
ProgramStateRef StateZero,
CheckerContext &C) const {
if (ExplodedNode *N = C.generateSink(StateZero)) {
if (!BT)
BT.reset(new BuiltinBug(this, "Division by zero"));
BugReport *R = new BugReport(*BT, Msg, N);
bugreporter::trackNullOrUndefValue(N, bugreporter::GetDenomExpr(N), *R);
C.emitReport(R);
}
}
void DivZeroChecker::checkPreStmt(const BinaryOperator *B,
CheckerContext &C) const {
BinaryOperator::Opcode Op = B->getOpcode();
if (Op != BO_Div &&
Op != BO_Rem &&
Op != BO_DivAssign &&
Op != BO_RemAssign)
return;
if (!B->getRHS()->getType()->isScalarType())
return;
SVal Denom = C.getState()->getSVal(B->getRHS(), C.getLocationContext());
Optional<DefinedSVal> DV = Denom.getAs<DefinedSVal>();
// Divide-by-undefined handled in the generic checking for uses of
// undefined values.
if (!DV)
return;
// Check for divide by zero.
ConstraintManager &CM = C.getConstraintManager();
ProgramStateRef stateNotZero, stateZero;
std::tie(stateNotZero, stateZero) = CM.assumeDual(C.getState(), *DV);
if (!stateNotZero) {
assert(stateZero);
reportBug("Division by zero", stateZero, C);
return;
}
bool TaintedD = C.getState()->isTainted(*DV);
if ((stateNotZero && stateZero && TaintedD)) {
reportBug("Division by a tainted value, possibly zero", stateZero, C);
return;
}
// If we get here, then the denom should not be zero. We abandon the implicit
// zero denom case for now.
C.addTransition(stateNotZero);
}
void ento::registerDivZeroChecker(CheckerManager &mgr) {
mgr.registerChecker<DivZeroChecker>();
}
|
