1 files changed, 193 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/ObjCContainersChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ObjCContainersChecker.cpp
new file mode 100644
index 000000000000..8abb926d4862
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/ObjCContainersChecker.cpp
@@ -0,0 +1,193 @@
+//== ObjCContainersChecker.cpp - Path sensitive checker for CFArray *- C++ -*=//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Performs path sensitive checks of Core Foundation static containers like
+// CFArray.
+// 1) Check for buffer overflows:
+//      In CFArrayGetArrayAtIndex( myArray, index), if the index is outside the
+//      index space of theArray (0 to N-1 inclusive (where N is the count of
+//      theArray), the behavior is undefined.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/AST/ParentMap.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"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class ObjCContainersChecker : public Checker< check::PreStmt<CallExpr>,
+                                             check::PostStmt<CallExpr>,
+                                             check::PointerEscape> {
+  mutable std::unique_ptr<BugType> BT;
+  inline void initBugType() const {
+    if (!BT)
+      BT.reset(new BugType(this, "CFArray API",
+                           categories::CoreFoundationObjectiveC));
+  }
+
+  inline SymbolRef getArraySym(const Expr *E, CheckerContext &C) const {
+    SVal ArrayRef = C.getSVal(E);
+    SymbolRef ArraySym = ArrayRef.getAsSymbol();
+    return ArraySym;
+  }
+
+  void addSizeInfo(const Expr *Array, const Expr *Size,
+                   CheckerContext &C) const;
+
+public:
+  /// A tag to id this checker.
+  static void *getTag() { static int Tag; return &Tag; }
+
+  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
+  void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
+  ProgramStateRef checkPointerEscape(ProgramStateRef State,
+                                     const InvalidatedSymbols &Escaped,
+                                     const CallEvent *Call,
+                                     PointerEscapeKind Kind) const;
+
+  void printState(raw_ostream &OS, ProgramStateRef State,
+                  const char *NL, const char *Sep) const;
+};
+} // end anonymous namespace
+
+// ProgramState trait - a map from array symbol to its state.
+REGISTER_MAP_WITH_PROGRAMSTATE(ArraySizeMap, SymbolRef, DefinedSVal)
+
+void ObjCContainersChecker::addSizeInfo(const Expr *Array, const Expr *Size,
+                                        CheckerContext &C) const {
+  ProgramStateRef State = C.getState();
+  SVal SizeV = C.getSVal(Size);
+  // Undefined is reported by another checker.
+  if (SizeV.isUnknownOrUndef())
+    return;
+
+  // Get the ArrayRef symbol.
+  SVal ArrayRef = C.getSVal(Array);
+  SymbolRef ArraySym = ArrayRef.getAsSymbol();
+  if (!ArraySym)
+    return;
+
+  C.addTransition(
+      State->set<ArraySizeMap>(ArraySym, SizeV.castAs<DefinedSVal>()));
+}
+
+void ObjCContainersChecker::checkPostStmt(const CallExpr *CE,
+                                          CheckerContext &C) const {
+  StringRef Name = C.getCalleeName(CE);
+  if (Name.empty() || CE->getNumArgs() < 1)
+    return;
+
+  // Add array size information to the state.
+  if (Name.equals("CFArrayCreate")) {
+    if (CE->getNumArgs() < 3)
+      return;
+    // Note, we can visit the Create method in the post-visit because
+    // the CFIndex parameter is passed in by value and will not be invalidated
+    // by the call.
+    addSizeInfo(CE, CE->getArg(2), C);
+    return;
+  }
+
+  if (Name.equals("CFArrayGetCount")) {
+    addSizeInfo(CE->getArg(0), CE, C);
+    return;
+  }
+}
+
+void ObjCContainersChecker::checkPreStmt(const CallExpr *CE,
+                                         CheckerContext &C) const {
+  StringRef Name = C.getCalleeName(CE);
+  if (Name.empty() || CE->getNumArgs() < 2)
+    return;
+
+  // Check the array access.
+  if (Name.equals("CFArrayGetValueAtIndex")) {
+    ProgramStateRef State = C.getState();
+    // Retrieve the size.
+    // Find out if we saw this array symbol before and have information about
+    // it.
+    const Expr *ArrayExpr = CE->getArg(0);
+    SymbolRef ArraySym = getArraySym(ArrayExpr, C);
+    if (!ArraySym)
+      return;
+
+    const DefinedSVal *Size = State->get<ArraySizeMap>(ArraySym);
+
+    if (!Size)
+      return;
+
+    // Get the index.
+    const Expr *IdxExpr = CE->getArg(1);
+    SVal IdxVal = C.getSVal(IdxExpr);
+    if (IdxVal.isUnknownOrUndef())
+      return;
+    DefinedSVal Idx = IdxVal.castAs<DefinedSVal>();
+
+    // Now, check if 'Idx in [0, Size-1]'.
+    const QualType T = IdxExpr->getType();
+    ProgramStateRef StInBound = State->assumeInBound(Idx, *Size, true, T);
+    ProgramStateRef StOutBound = State->assumeInBound(Idx, *Size, false, T);
+    if (StOutBound && !StInBound) {
+      ExplodedNode *N = C.generateErrorNode(StOutBound);
+      if (!N)
+        return;
+      initBugType();
+      auto R = std::make_unique<PathSensitiveBugReport>(
+          *BT, "Index is out of bounds", N);
+      R->addRange(IdxExpr->getSourceRange());
+      bugreporter::trackExpressionValue(
+          N, IdxExpr, *R, bugreporter::TrackingKind::Thorough, false);
+      C.emitReport(std::move(R));
+      return;
+    }
+  }
+}
+
+ProgramStateRef
+ObjCContainersChecker::checkPointerEscape(ProgramStateRef State,
+                                          const InvalidatedSymbols &Escaped,
+                                          const CallEvent *Call,
+                                          PointerEscapeKind Kind) const {
+  for (const auto &Sym : Escaped) {
+    // When a symbol for a mutable array escapes, we can't reason precisely
+    // about its size any more -- so remove it from the map.
+    // Note that we aren't notified here when a CFMutableArrayRef escapes as a
+    // CFArrayRef. This is because CFArrayRef is typedef'd as a pointer to a
+    // const-qualified type.
+    State = State->remove<ArraySizeMap>(Sym);
+  }
+  return State;
+}
+
+void ObjCContainersChecker::printState(raw_ostream &OS, ProgramStateRef State,
+                                       const char *NL, const char *Sep) const {
+  ArraySizeMapTy Map = State->get<ArraySizeMap>();
+  if (Map.isEmpty())
+    return;
+
+  OS << Sep << "ObjC container sizes :" << NL;
+  for (auto I : Map) {
+    OS << I.first << " : " << I.second << NL;
+  }
+}
+
+/// Register checker.
+void ento::registerObjCContainersChecker(CheckerManager &mgr) {
+  mgr.registerChecker<ObjCContainersChecker>();
+}
+
+bool ento::shouldRegisterObjCContainersChecker(const LangOptions &LO) {
+  return true;
+}