clang  6.0.0svn
ReturnPointerRangeChecker.cpp
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1 //== ReturnPointerRangeChecker.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 file defines ReturnPointerRangeChecker, which is a path-sensitive check
11 // which looks for an out-of-bound pointer being returned to callers.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "ClangSACheckers.h"
21 
22 using namespace clang;
23 using namespace ento;
24 
25 namespace {
26 class ReturnPointerRangeChecker :
27  public Checker< check::PreStmt<ReturnStmt> > {
28  mutable std::unique_ptr<BuiltinBug> BT;
29 
30 public:
31  void checkPreStmt(const ReturnStmt *RS, CheckerContext &C) const;
32 };
33 }
34 
35 void ReturnPointerRangeChecker::checkPreStmt(const ReturnStmt *RS,
36  CheckerContext &C) const {
38 
39  const Expr *RetE = RS->getRetValue();
40  if (!RetE)
41  return;
42 
43  SVal V = state->getSVal(RetE, C.getLocationContext());
44  const MemRegion *R = V.getAsRegion();
45 
46  const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(R);
47  if (!ER)
48  return;
49 
51  // Zero index is always in bound, this also passes ElementRegions created for
52  // pointer casts.
53  if (Idx.isZeroConstant())
54  return;
55  // FIXME: All of this out-of-bounds checking should eventually be refactored
56  // into a common place.
57 
58  DefinedOrUnknownSVal NumElements
60  ER->getValueType());
61 
62  ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true);
63  ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false);
64  if (StOutBound && !StInBound) {
65  ExplodedNode *N = C.generateErrorNode(StOutBound);
66 
67  if (!N)
68  return;
69 
70  // FIXME: This bug correspond to CWE-466. Eventually we should have bug
71  // types explicitly reference such exploit categories (when applicable).
72  if (!BT)
73  BT.reset(new BuiltinBug(
74  this, "Return of pointer value outside of expected range",
75  "Returned pointer value points outside the original object "
76  "(potential buffer overflow)"));
77 
78  // FIXME: It would be nice to eventually make this diagnostic more clear,
79  // e.g., by referencing the original declaration or by saying *why* this
80  // reference is outside the range.
81 
82  // Generate a report for this bug.
83  auto report = llvm::make_unique<BugReport>(*BT, BT->getDescription(), N);
84 
85  report->addRange(RetE->getSourceRange());
86  C.emitReport(std::move(report));
87  }
88 }
89 
90 void ento::registerReturnPointerRangeChecker(CheckerManager &mgr) {
91  mgr.registerChecker<ReturnPointerRangeChecker>();
92 }
virtual DefinedOrUnknownSVal getSizeInElements(ProgramStateRef state, const MemRegion *region, QualType EleTy)
Definition: Store.h:129
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
const MemRegion * getSuperRegion() const
Definition: MemRegion.h:430
const Expr * getRetValue() const
Definition: Stmt.cpp:925
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
Expr - This represents one expression.
Definition: Expr.h:106
ReturnStmt - This represents a return, optionally of an expression: return; return 4;...
Definition: Stmt.h:1413
void emitReport(std::unique_ptr< BugReport > R)
Emit the diagnostics report.
CHECKER * registerChecker()
Used to register checkers.
StoreManager & getStoreManager()
const MemRegion * getAsRegion() const
Definition: SVals.cpp:140
SVal - This represents a symbolic expression, which can be either an L-value or an R-value...
Definition: SVals.h:63
Dataflow Directional Tag Classes.
bool isZeroConstant() const
Definition: SVals.cpp:219
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
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:265
ElementRegin is used to represent both array elements and casts.
Definition: MemRegion.h:1066
const LocationContext * getLocationContext() const