1 files changed, 106 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
new file mode 100644
index 000000000000..8798bde88dcd
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
@@ -0,0 +1,106 @@
+//== DivZeroChecker.cpp - Division by zero checker --------------*- 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 defines DivZeroChecker, a builtin check in ExprEngine that performs
+// checks for division by zeros.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Taint.h"
+#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"
+
+using namespace clang;
+using namespace ento;
+using namespace taint;
+
+namespace {
+class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
+  mutable std::unique_ptr<BuiltinBug> BT;
+  void reportBug(const char *Msg, ProgramStateRef StateZero, CheckerContext &C,
+                 std::unique_ptr<BugReporterVisitor> Visitor = nullptr) const;
+
+public:
+  void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
+};
+} // end anonymous namespace
+
+static const Expr *getDenomExpr(const ExplodedNode *N) {
+  const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
+  if (const auto *BE = dyn_cast<BinaryOperator>(S))
+    return BE->getRHS();
+  return nullptr;
+}
+
+void DivZeroChecker::reportBug(
+    const char *Msg, ProgramStateRef StateZero, CheckerContext &C,
+    std::unique_ptr<BugReporterVisitor> Visitor) const {
+  if (ExplodedNode *N = C.generateErrorNode(StateZero)) {
+    if (!BT)
+      BT.reset(new BuiltinBug(this, "Division by zero"));
+
+    auto R = std::make_unique<PathSensitiveBugReport>(*BT, Msg, N);
+    R->addVisitor(std::move(Visitor));
+    bugreporter::trackExpressionValue(N, getDenomExpr(N), *R);
+    C.emitReport(std::move(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.getSVal(B->getRHS());
+  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 = isTainted(C.getState(), *DV);
+  if ((stateNotZero && stateZero && TaintedD)) {
+    reportBug("Division by a tainted value, possibly zero", stateZero, C,
+              std::make_unique<taint::TaintBugVisitor>(*DV));
+    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>();
+}
+
+bool ento::shouldRegisterDivZeroChecker(const LangOptions &LO) {
+  return true;
+}