clang  6.0.0svn
UndefResultChecker.cpp
Go to the documentation of this file.
1 //=== UndefResultChecker.cpp ------------------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This defines UndefResultChecker, a builtin check in ExprEngine that
11 // performs checks for undefined results of non-assignment binary operators.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "ClangSACheckers.h"
21 #include "llvm/ADT/SmallString.h"
22 #include "llvm/Support/raw_ostream.h"
23 
24 using namespace clang;
25 using namespace ento;
26 
27 namespace {
28 class UndefResultChecker
29  : public Checker< check::PostStmt<BinaryOperator> > {
30 
31  mutable std::unique_ptr<BugType> BT;
32 
33 public:
34  void checkPostStmt(const BinaryOperator *B, CheckerContext &C) const;
35 };
36 } // end anonymous namespace
37 
38 static bool isArrayIndexOutOfBounds(CheckerContext &C, const Expr *Ex) {
40  const LocationContext *LCtx = C.getLocationContext();
41 
42  if (!isa<ArraySubscriptExpr>(Ex))
43  return false;
44 
45  SVal Loc = state->getSVal(Ex, LCtx);
46  if (!Loc.isValid())
47  return false;
48 
49  const MemRegion *MR = Loc.castAs<loc::MemRegionVal>().getRegion();
50  const ElementRegion *ER = dyn_cast<ElementRegion>(MR);
51  if (!ER)
52  return false;
53 
56  state, ER->getSuperRegion(), ER->getValueType());
57  ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true);
58  ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false);
59  return StOutBound && !StInBound;
60 }
61 
62 void UndefResultChecker::checkPostStmt(const BinaryOperator *B,
63  CheckerContext &C) const {
65  const LocationContext *LCtx = C.getLocationContext();
66  if (state->getSVal(B, LCtx).isUndef()) {
67 
68  // Do not report assignments of uninitialized values inside swap functions.
69  // This should allow to swap partially uninitialized structs
70  // (radar://14129997)
71  if (const FunctionDecl *EnclosingFunctionDecl =
72  dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl()))
73  if (C.getCalleeName(EnclosingFunctionDecl) == "swap")
74  return;
75 
76  // Generate an error node.
78  if (!N)
79  return;
80 
81  if (!BT)
82  BT.reset(
83  new BuiltinBug(this, "Result of operation is garbage or undefined"));
84 
85  SmallString<256> sbuf;
86  llvm::raw_svector_ostream OS(sbuf);
87  const Expr *Ex = nullptr;
88  bool isLeft = true;
89 
90  if (state->getSVal(B->getLHS(), LCtx).isUndef()) {
91  Ex = B->getLHS()->IgnoreParenCasts();
92  isLeft = true;
93  }
94  else if (state->getSVal(B->getRHS(), LCtx).isUndef()) {
95  Ex = B->getRHS()->IgnoreParenCasts();
96  isLeft = false;
97  }
98 
99  if (Ex) {
100  OS << "The " << (isLeft ? "left" : "right")
101  << " operand of '"
103  << "' is a garbage value";
104  if (isArrayIndexOutOfBounds(C, Ex))
105  OS << " due to array index out of bounds";
106  }
107  else {
108  // Neither operand was undefined, but the result is undefined.
109  OS << "The result of the '"
111  << "' expression is undefined";
112  }
113  auto report = llvm::make_unique<BugReport>(*BT, OS.str(), N);
114  if (Ex) {
115  report->addRange(Ex->getSourceRange());
116  bugreporter::trackNullOrUndefValue(N, Ex, *report);
117  }
118  else
119  bugreporter::trackNullOrUndefValue(N, B, *report);
120 
121  C.emitReport(std::move(report));
122  }
123 }
124 
125 void ento::registerUndefResultChecker(CheckerManager &mgr) {
126  mgr.registerChecker<UndefResultChecker>();
127 }
virtual DefinedOrUnknownSVal getSizeInElements(ProgramStateRef state, const MemRegion *region, QualType EleTy)
Definition: Store.h:129
FunctionDecl - An instance of this class is created to represent a function declaration or definition...
Definition: Decl.h:1629
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:79
ExplodedNode * generateErrorNode(ProgramStateRef State=nullptr, const ProgramPointTag *Tag=nullptr)
Generate a transition to a node that will be used to report an error.
NonLoc getIndex() const
Definition: MemRegion.h:1085
Opcode getOpcode() const
Definition: Expr.h:3021
const MemRegion * getSuperRegion() const
Definition: MemRegion.h:430
StringRef getCalleeName(const FunctionDecl *FunDecl) const
Get the name of the called function (path-sensitive).
i32 captured_struct **param SharedsTy A type which contains references the shared variables *param Shareds Context with the list of shared variables from the p *TaskFunction *param Data Additional data for task generation like final * state
StringRef getOpcodeStr() const
Definition: Expr.h:3040
static bool isArrayIndexOutOfBounds(CheckerContext &C, const Expr *Ex)
A builtin binary operation expression such as "x + y" or "x <= y".
Definition: Expr.h:2980
Expr * IgnoreParenCasts() LLVM_READONLY
IgnoreParenCasts - Ignore parentheses and casts.
Definition: Expr.cpp:2451
Expr - This represents one expression.
Definition: Expr.h:106
bool isValid() const
Definition: SVals.h:140
void emitReport(std::unique_ptr< BugReport > R)
Emit the diagnostics report.
CHECKER * registerChecker()
Used to register checkers.
StoreManager & getStoreManager()
SVal - This represents a symbolic expression, which can be either an L-value or an R-value...
Definition: SVals.h:63
Expr * getLHS() const
Definition: Expr.h:3024
Dataflow Directional Tag Classes.
const Decl * getDecl() const
const StackFrameContext * getStackFrame() const
T castAs() const
Convert to the specified SVal type, asserting that this SVal is of the desired type.
Definition: SVals.h:92
const ProgramStateRef & getState() const
bool trackNullOrUndefValue(const ExplodedNode *N, const Stmt *S, BugReport &R, bool IsArg=false, bool EnableNullFPSuppression=true)
Attempts to add visitors to trace a null or undefined value back to its point of origin, whether it is a symbol constrained to null or an explicit assignment.
QualType getValueType() const override
Definition: MemRegion.h:1087
SourceRange getSourceRange() const LLVM_READONLY
SourceLocation tokens are not useful in isolation - they are low level value objects created/interpre...
Definition: Stmt.cpp:245
ElementRegin is used to represent both array elements and casts.
Definition: MemRegion.h:1066
Expr * getRHS() const
Definition: Expr.h:3026
const LocationContext * getLocationContext() const