1 files changed, 443 insertions, 0 deletions
diff --git a/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/StackAddrEscapeChecker.cpp b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/StackAddrEscapeChecker.cpp
new file mode 100644
index 000000000000..ea09c43cc5ce
--- /dev/null
+++ b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/StackAddrEscapeChecker.cpp
@@ -0,0 +1,443 @@
+//=== StackAddrEscapeChecker.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 stack address leak checker, which checks if an invalid
+// stack address is stored into a global or heap location. See CERT DCL30-C.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ExprCXX.h"
+#include "clang/Basic/SourceManager.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/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace clang;
+using namespace ento;
+
+namespace {
+class StackAddrEscapeChecker
+    : public Checker<check::PreCall, check::PreStmt<ReturnStmt>,
+                     check::EndFunction> {
+  mutable IdentifierInfo *dispatch_semaphore_tII = nullptr;
+  mutable std::unique_ptr<BugType> BT_stackleak;
+  mutable std::unique_ptr<BugType> BT_returnstack;
+  mutable std::unique_ptr<BugType> BT_capturedstackasync;
+  mutable std::unique_ptr<BugType> BT_capturedstackret;
+
+public:
+  enum CheckKind {
+    CK_StackAddrEscapeChecker,
+    CK_StackAddrAsyncEscapeChecker,
+    CK_NumCheckKinds
+  };
+
+  bool ChecksEnabled[CK_NumCheckKinds] = {false};
+  CheckerNameRef CheckNames[CK_NumCheckKinds];
+
+  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
+  void checkPreStmt(const ReturnStmt *RS, CheckerContext &C) const;
+  void checkEndFunction(const ReturnStmt *RS, CheckerContext &Ctx) const;
+
+private:
+  void checkReturnedBlockCaptures(const BlockDataRegion &B,
+                                  CheckerContext &C) const;
+  void checkAsyncExecutedBlockCaptures(const BlockDataRegion &B,
+                                       CheckerContext &C) const;
+  void EmitStackError(CheckerContext &C, const MemRegion *R,
+                      const Expr *RetE) const;
+  bool isSemaphoreCaptured(const BlockDecl &B) const;
+  static SourceRange genName(raw_ostream &os, const MemRegion *R,
+                             ASTContext &Ctx);
+  static SmallVector<const MemRegion *, 4>
+  getCapturedStackRegions(const BlockDataRegion &B, CheckerContext &C);
+  static bool isNotInCurrentFrame(const MemRegion *R, CheckerContext &C);
+};
+} // namespace
+
+SourceRange StackAddrEscapeChecker::genName(raw_ostream &os, const MemRegion *R,
+                                            ASTContext &Ctx) {
+  // Get the base region, stripping away fields and elements.
+  R = R->getBaseRegion();
+  SourceManager &SM = Ctx.getSourceManager();
+  SourceRange range;
+  os << "Address of ";
+
+  // Check if the region is a compound literal.
+  if (const auto *CR = dyn_cast<CompoundLiteralRegion>(R)) {
+    const CompoundLiteralExpr *CL = CR->getLiteralExpr();
+    os << "stack memory associated with a compound literal "
+          "declared on line "
+       << SM.getExpansionLineNumber(CL->getBeginLoc()) << " returned to caller";
+    range = CL->getSourceRange();
+  } else if (const auto *AR = dyn_cast<AllocaRegion>(R)) {
+    const Expr *ARE = AR->getExpr();
+    SourceLocation L = ARE->getBeginLoc();
+    range = ARE->getSourceRange();
+    os << "stack memory allocated by call to alloca() on line "
+       << SM.getExpansionLineNumber(L);
+  } else if (const auto *BR = dyn_cast<BlockDataRegion>(R)) {
+    const BlockDecl *BD = BR->getCodeRegion()->getDecl();
+    SourceLocation L = BD->getBeginLoc();
+    range = BD->getSourceRange();
+    os << "stack-allocated block declared on line "
+       << SM.getExpansionLineNumber(L);
+  } else if (const auto *VR = dyn_cast<VarRegion>(R)) {
+    os << "stack memory associated with local variable '" << VR->getString()
+       << '\'';
+    range = VR->getDecl()->getSourceRange();
+  } else if (const auto *LER = dyn_cast<CXXLifetimeExtendedObjectRegion>(R)) {
+    QualType Ty = LER->getValueType().getLocalUnqualifiedType();
+    os << "stack memory associated with temporary object of type '";
+    Ty.print(os, Ctx.getPrintingPolicy());
+    os << "' lifetime extended by local variable";
+    if (const IdentifierInfo *ID = LER->getExtendingDecl()->getIdentifier())
+      os << " '" << ID->getName() << '\'';
+    range = LER->getExpr()->getSourceRange();
+  } else if (const auto *TOR = dyn_cast<CXXTempObjectRegion>(R)) {
+    QualType Ty = TOR->getValueType().getLocalUnqualifiedType();
+    os << "stack memory associated with temporary object of type '";
+    Ty.print(os, Ctx.getPrintingPolicy());
+    os << "'";
+    range = TOR->getExpr()->getSourceRange();
+  } else {
+    llvm_unreachable("Invalid region in ReturnStackAddressChecker.");
+  }
+
+  return range;
+}
+
+bool StackAddrEscapeChecker::isNotInCurrentFrame(const MemRegion *R,
+                                                 CheckerContext &C) {
+  const StackSpaceRegion *S = cast<StackSpaceRegion>(R->getMemorySpace());
+  return S->getStackFrame() != C.getStackFrame();
+}
+
+bool StackAddrEscapeChecker::isSemaphoreCaptured(const BlockDecl &B) const {
+  if (!dispatch_semaphore_tII)
+    dispatch_semaphore_tII = &B.getASTContext().Idents.get("dispatch_semaphore_t");
+  for (const auto &C : B.captures()) {
+    const auto *T = C.getVariable()->getType()->getAs<TypedefType>();
+    if (T && T->getDecl()->getIdentifier() == dispatch_semaphore_tII)
+      return true;
+  }
+  return false;
+}
+
+SmallVector<const MemRegion *, 4>
+StackAddrEscapeChecker::getCapturedStackRegions(const BlockDataRegion &B,
+                                                CheckerContext &C) {
+  SmallVector<const MemRegion *, 4> Regions;
+  for (auto Var : B.referenced_vars()) {
+    SVal Val = C.getState()->getSVal(Var.getCapturedRegion());
+    const MemRegion *Region = Val.getAsRegion();
+    if (Region && isa<StackSpaceRegion>(Region->getMemorySpace()))
+      Regions.push_back(Region);
+  }
+  return Regions;
+}
+
+void StackAddrEscapeChecker::EmitStackError(CheckerContext &C,
+                                            const MemRegion *R,
+                                            const Expr *RetE) const {
+  ExplodedNode *N = C.generateNonFatalErrorNode();
+  if (!N)
+    return;
+  if (!BT_returnstack)
+    BT_returnstack = std::make_unique<BugType>(
+        CheckNames[CK_StackAddrEscapeChecker],
+        "Return of address to stack-allocated memory");
+  // Generate a report for this bug.
+  SmallString<128> buf;
+  llvm::raw_svector_ostream os(buf);
+  SourceRange range = genName(os, R, C.getASTContext());
+  os << " returned to caller";
+  auto report =
+      std::make_unique<PathSensitiveBugReport>(*BT_returnstack, os.str(), N);
+  report->addRange(RetE->getSourceRange());
+  if (range.isValid())
+    report->addRange(range);
+  C.emitReport(std::move(report));
+}
+
+void StackAddrEscapeChecker::checkAsyncExecutedBlockCaptures(
+    const BlockDataRegion &B, CheckerContext &C) const {
+  // There is a not-too-uncommon idiom
+  // where a block passed to dispatch_async captures a semaphore
+  // and then the thread (which called dispatch_async) is blocked on waiting
+  // for the completion of the execution of the block
+  // via dispatch_semaphore_wait. To avoid false-positives (for now)
+  // we ignore all the blocks which have captured
+  // a variable of the type "dispatch_semaphore_t".
+  if (isSemaphoreCaptured(*B.getDecl()))
+    return;
+  for (const MemRegion *Region : getCapturedStackRegions(B, C)) {
+    // The block passed to dispatch_async may capture another block
+    // created on the stack. However, there is no leak in this situaton,
+    // no matter if ARC or no ARC is enabled:
+    // dispatch_async copies the passed "outer" block (via Block_copy)
+    // and if the block has captured another "inner" block,
+    // the "inner" block will be copied as well.
+    if (isa<BlockDataRegion>(Region))
+      continue;
+    ExplodedNode *N = C.generateNonFatalErrorNode();
+    if (!N)
+      continue;
+    if (!BT_capturedstackasync)
+      BT_capturedstackasync = std::make_unique<BugType>(
+          CheckNames[CK_StackAddrAsyncEscapeChecker],
+          "Address of stack-allocated memory is captured");
+    SmallString<128> Buf;
+    llvm::raw_svector_ostream Out(Buf);
+    SourceRange Range = genName(Out, Region, C.getASTContext());
+    Out << " is captured by an asynchronously-executed block";
+    auto Report = std::make_unique<PathSensitiveBugReport>(
+        *BT_capturedstackasync, Out.str(), N);
+    if (Range.isValid())
+      Report->addRange(Range);
+    C.emitReport(std::move(Report));
+  }
+}
+
+void StackAddrEscapeChecker::checkReturnedBlockCaptures(
+    const BlockDataRegion &B, CheckerContext &C) const {
+  for (const MemRegion *Region : getCapturedStackRegions(B, C)) {
+    if (isNotInCurrentFrame(Region, C))
+      continue;
+    ExplodedNode *N = C.generateNonFatalErrorNode();
+    if (!N)
+      continue;
+    if (!BT_capturedstackret)
+      BT_capturedstackret = std::make_unique<BugType>(
+          CheckNames[CK_StackAddrEscapeChecker],
+          "Address of stack-allocated memory is captured");
+    SmallString<128> Buf;
+    llvm::raw_svector_ostream Out(Buf);
+    SourceRange Range = genName(Out, Region, C.getASTContext());
+    Out << " is captured by a returned block";
+    auto Report = std::make_unique<PathSensitiveBugReport>(*BT_capturedstackret,
+                                                           Out.str(), N);
+    if (Range.isValid())
+      Report->addRange(Range);
+    C.emitReport(std::move(Report));
+  }
+}
+
+void StackAddrEscapeChecker::checkPreCall(const CallEvent &Call,
+                                          CheckerContext &C) const {
+  if (!ChecksEnabled[CK_StackAddrAsyncEscapeChecker])
+    return;
+  if (!Call.isGlobalCFunction("dispatch_after") &&
+      !Call.isGlobalCFunction("dispatch_async"))
+    return;
+  for (unsigned Idx = 0, NumArgs = Call.getNumArgs(); Idx < NumArgs; ++Idx) {
+    if (const BlockDataRegion *B = dyn_cast_or_null<BlockDataRegion>(
+            Call.getArgSVal(Idx).getAsRegion()))
+      checkAsyncExecutedBlockCaptures(*B, C);
+  }
+}
+
+void StackAddrEscapeChecker::checkPreStmt(const ReturnStmt *RS,
+                                          CheckerContext &C) const {
+  if (!ChecksEnabled[CK_StackAddrEscapeChecker])
+    return;
+
+  const Expr *RetE = RS->getRetValue();
+  if (!RetE)
+    return;
+  RetE = RetE->IgnoreParens();
+
+  SVal V = C.getSVal(RetE);
+  const MemRegion *R = V.getAsRegion();
+  if (!R)
+    return;
+
+  if (const BlockDataRegion *B = dyn_cast<BlockDataRegion>(R))
+    checkReturnedBlockCaptures(*B, C);
+
+  if (!isa<StackSpaceRegion>(R->getMemorySpace()) || isNotInCurrentFrame(R, C))
+    return;
+
+  // Returning a record by value is fine. (In this case, the returned
+  // expression will be a copy-constructor, possibly wrapped in an
+  // ExprWithCleanups node.)
+  if (const ExprWithCleanups *Cleanup = dyn_cast<ExprWithCleanups>(RetE))
+    RetE = Cleanup->getSubExpr();
+  if (isa<CXXConstructExpr>(RetE) && RetE->getType()->isRecordType())
+    return;
+
+  // The CK_CopyAndAutoreleaseBlockObject cast causes the block to be copied
+  // so the stack address is not escaping here.
+  if (const auto *ICE = dyn_cast<ImplicitCastExpr>(RetE)) {
+    if (isa<BlockDataRegion>(R) &&
+        ICE->getCastKind() == CK_CopyAndAutoreleaseBlockObject) {
+      return;
+    }
+  }
+
+  EmitStackError(C, R, RetE);
+}
+
+void StackAddrEscapeChecker::checkEndFunction(const ReturnStmt *RS,
+                                              CheckerContext &Ctx) const {
+  if (!ChecksEnabled[CK_StackAddrEscapeChecker])
+    return;
+
+  ProgramStateRef State = Ctx.getState();
+
+  // Iterate over all bindings to global variables and see if it contains
+  // a memory region in the stack space.
+  class CallBack : public StoreManager::BindingsHandler {
+  private:
+    CheckerContext &Ctx;
+    const StackFrameContext *PoppedFrame;
+
+    /// Look for stack variables referring to popped stack variables.
+    /// Returns true only if it found some dangling stack variables
+    /// referred by an other stack variable from different stack frame.
+    bool checkForDanglingStackVariable(const MemRegion *Referrer,
+                                       const MemRegion *Referred) {
+      const auto *ReferrerMemSpace =
+          Referrer->getMemorySpace()->getAs<StackSpaceRegion>();
+      const auto *ReferredMemSpace =
+          Referred->getMemorySpace()->getAs<StackSpaceRegion>();
+
+      if (!ReferrerMemSpace || !ReferredMemSpace)
+        return false;
+
+      const auto *ReferrerFrame = ReferrerMemSpace->getStackFrame();
+      const auto *ReferredFrame = ReferredMemSpace->getStackFrame();
+
+      if (ReferrerMemSpace && ReferredMemSpace) {
+        if (ReferredFrame == PoppedFrame &&
+            ReferrerFrame->isParentOf(PoppedFrame)) {
+          V.emplace_back(Referrer, Referred);
+          return true;
+        }
+      }
+      return false;
+    }
+
+  public:
+    SmallVector<std::pair<const MemRegion *, const MemRegion *>, 10> V;
+
+    CallBack(CheckerContext &CC) : Ctx(CC), PoppedFrame(CC.getStackFrame()) {}
+
+    bool HandleBinding(StoreManager &SMgr, Store S, const MemRegion *Region,
+                       SVal Val) override {
+      const MemRegion *VR = Val.getAsRegion();
+      if (!VR)
+        return true;
+
+      if (checkForDanglingStackVariable(Region, VR))
+        return true;
+
+      // Check the globals for the same.
+      if (!isa<GlobalsSpaceRegion>(Region->getMemorySpace()))
+        return true;
+      if (VR && VR->hasStackStorage() && !isNotInCurrentFrame(VR, Ctx))
+        V.emplace_back(Region, VR);
+      return true;
+    }
+  };
+
+  CallBack Cb(Ctx);
+  State->getStateManager().getStoreManager().iterBindings(State->getStore(),
+                                                          Cb);
+
+  if (Cb.V.empty())
+    return;
+
+  // Generate an error node.
+  ExplodedNode *N = Ctx.generateNonFatalErrorNode(State);
+  if (!N)
+    return;
+
+  if (!BT_stackleak)
+    BT_stackleak =
+        std::make_unique<BugType>(CheckNames[CK_StackAddrEscapeChecker],
+                                  "Stack address stored into global variable");
+
+  for (const auto &P : Cb.V) {
+    const MemRegion *Referrer = P.first->getBaseRegion();
+    const MemRegion *Referred = P.second;
+
+    // Generate a report for this bug.
+    const StringRef CommonSuffix =
+        "upon returning to the caller.  This will be a dangling reference";
+    SmallString<128> Buf;
+    llvm::raw_svector_ostream Out(Buf);
+    const SourceRange Range = genName(Out, Referred, Ctx.getASTContext());
+
+    if (isa<CXXTempObjectRegion, CXXLifetimeExtendedObjectRegion>(Referrer)) {
+      Out << " is still referred to by a temporary object on the stack "
+          << CommonSuffix;
+      auto Report =
+          std::make_unique<PathSensitiveBugReport>(*BT_stackleak, Out.str(), N);
+      if (Range.isValid())
+        Report->addRange(Range);
+      Ctx.emitReport(std::move(Report));
+      return;
+    }
+
+    const StringRef ReferrerMemorySpace = [](const MemSpaceRegion *Space) {
+      if (isa<StaticGlobalSpaceRegion>(Space))
+        return "static";
+      if (isa<GlobalsSpaceRegion>(Space))
+        return "global";
+      assert(isa<StackSpaceRegion>(Space));
+      return "stack";
+    }(Referrer->getMemorySpace());
+
+    // We should really only have VarRegions here.
+    // Anything else is really surprising, and we should get notified if such
+    // ever happens.
+    const auto *ReferrerVar = dyn_cast<VarRegion>(Referrer);
+    if (!ReferrerVar) {
+      assert(false && "We should have a VarRegion here");
+      continue; // Defensively skip this one.
+    }
+    const std::string ReferrerVarName =
+        ReferrerVar->getDecl()->getDeclName().getAsString();
+
+    Out << " is still referred to by the " << ReferrerMemorySpace
+        << " variable '" << ReferrerVarName << "' " << CommonSuffix;
+    auto Report =
+        std::make_unique<PathSensitiveBugReport>(*BT_stackleak, Out.str(), N);
+    if (Range.isValid())
+      Report->addRange(Range);
+
+    Ctx.emitReport(std::move(Report));
+  }
+}
+
+void ento::registerStackAddrEscapeBase(CheckerManager &mgr) {
+  mgr.registerChecker<StackAddrEscapeChecker>();
+}
+
+bool ento::shouldRegisterStackAddrEscapeBase(const CheckerManager &mgr) {
+  return true;
+}
+
+#define REGISTER_CHECKER(name)                                                 \
+  void ento::register##name(CheckerManager &Mgr) {                             \
+    StackAddrEscapeChecker *Chk = Mgr.getChecker<StackAddrEscapeChecker>();    \
+    Chk->ChecksEnabled[StackAddrEscapeChecker::CK_##name] = true;              \
+    Chk->CheckNames[StackAddrEscapeChecker::CK_##name] =                       \
+        Mgr.getCurrentCheckerName();                                           \
+  }                                                                            \
+                                                                               \
+  bool ento::shouldRegister##name(const CheckerManager &mgr) { return true; }
+
+REGISTER_CHECKER(StackAddrEscapeChecker)
+REGISTER_CHECKER(StackAddrAsyncEscapeChecker)