1 files changed, 97 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/ArrayBoundChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ArrayBoundChecker.cpp
new file mode 100644
index 000000000000..8d4793e0802f
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/ArrayBoundChecker.cpp
@@ -0,0 +1,97 @@
+//== ArrayBoundChecker.cpp ------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines ArrayBoundChecker, which is a path-sensitive check
+// which looks for an out-of-bound array element access.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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/ExprEngine.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class ArrayBoundChecker :
+    public Checker<check::Location> {
+  mutable std::unique_ptr<BuiltinBug> BT;
+
+public:
+  void checkLocation(SVal l, bool isLoad, const Stmt* S,
+                     CheckerContext &C) const;
+};
+}
+
+void ArrayBoundChecker::checkLocation(SVal l, bool isLoad, const Stmt* LoadS,
+                                      CheckerContext &C) const {
+  // Check for out of bound array element access.
+  const MemRegion *R = l.getAsRegion();
+  if (!R)
+    return;
+
+  const ElementRegion *ER = dyn_cast<ElementRegion>(R);
+  if (!ER)
+    return;
+
+  // Get the index of the accessed element.
+  DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();
+
+  // Zero index is always in bound, this also passes ElementRegions created for
+  // pointer casts.
+  if (Idx.isZeroConstant())
+    return;
+
+  ProgramStateRef state = C.getState();
+
+  // Get the size of the array.
+  DefinedOrUnknownSVal NumElements
+    = C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(),
+                                            ER->getValueType());
+
+  ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true);
+  ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false);
+  if (StOutBound && !StInBound) {
+    ExplodedNode *N = C.generateErrorNode(StOutBound);
+    if (!N)
+      return;
+
+    if (!BT)
+      BT.reset(new BuiltinBug(
+          this, "Out-of-bound array access",
+          "Access out-of-bound array element (buffer overflow)"));
+
+    // FIXME: It would be nice to eventually make this diagnostic more clear,
+    // e.g., by referencing the original declaration or by saying *why* this
+    // reference is outside the range.
+
+    // Generate a report for this bug.
+    auto report =
+        std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N);
+
+    report->addRange(LoadS->getSourceRange());
+    C.emitReport(std::move(report));
+    return;
+  }
+
+  // Array bound check succeeded.  From this point forward the array bound
+  // should always succeed.
+  C.addTransition(StInBound);
+}
+
+void ento::registerArrayBoundChecker(CheckerManager &mgr) {
+  mgr.registerChecker<ArrayBoundChecker>();
+}
+
+bool ento::shouldRegisterArrayBoundChecker(const LangOptions &LO) {
+  return true;
+}