Merge branch 'master' of ssh://bitbucket.org/czan/honours

1 files changed, 230 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/StackAddrEscapeChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StackAddrEscapeChecker.cpp
new file mode 100644
index 0000000..54cf569
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/StackAddrEscapeChecker.cpp
@@ -0,0 +1,230 @@
+//=== StackAddrEscapeChecker.cpp ----------------------------------*- C++ -*--//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// 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 "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
+#include "clang/Basic/SourceManager.h"
+#include "llvm/ADT/SmallString.h"
+using namespace clang;
+using namespace ento;
+
+namespace {
+class StackAddrEscapeChecker : public Checker< check::PreStmt<ReturnStmt>,
+                                               check::EndPath > {
+  mutable OwningPtr<BuiltinBug> BT_stackleak;
+  mutable OwningPtr<BuiltinBug> BT_returnstack;
+
+public:
+  void checkPreStmt(const ReturnStmt *RS, CheckerContext &C) const;
+  void checkEndPath(CheckerContext &Ctx) const;
+private:
+  void EmitStackError(CheckerContext &C, const MemRegion *R,
+                      const Expr *RetE) const;
+  static SourceRange GenName(raw_ostream &os, const MemRegion *R,
+                             SourceManager &SM);
+};
+}
+
+SourceRange StackAddrEscapeChecker::GenName(raw_ostream &os,
+                                          const MemRegion *R,
+                                          SourceManager &SM) {
+    // Get the base region, stripping away fields and elements.
+  R = R->getBaseRegion();
+  SourceRange range;
+  os << "Address of ";
+  
+  // Check if the region is a compound literal.
+  if (const CompoundLiteralRegion* CR = dyn_cast<CompoundLiteralRegion>(R)) { 
+    const CompoundLiteralExpr *CL = CR->getLiteralExpr();
+    os << "stack memory associated with a compound literal "
+          "declared on line "
+        << SM.getExpansionLineNumber(CL->getLocStart())
+        << " returned to caller";    
+    range = CL->getSourceRange();
+  }
+  else if (const AllocaRegion* AR = dyn_cast<AllocaRegion>(R)) {
+    const Expr *ARE = AR->getExpr();
+    SourceLocation L = ARE->getLocStart();
+    range = ARE->getSourceRange();    
+    os << "stack memory allocated by call to alloca() on line "
+       << SM.getExpansionLineNumber(L);
+  }
+  else if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(R)) {
+    const BlockDecl *BD = BR->getCodeRegion()->getDecl();
+    SourceLocation L = BD->getLocStart();
+    range = BD->getSourceRange();
+    os << "stack-allocated block declared on line "
+       << SM.getExpansionLineNumber(L);
+  }
+  else if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
+    os << "stack memory associated with local variable '"
+       << VR->getString() << '\'';
+    range = VR->getDecl()->getSourceRange();
+  }
+  else if (const CXXTempObjectRegion *TOR = dyn_cast<CXXTempObjectRegion>(R)) {
+    os << "stack memory associated with temporary object of type '"
+       << TOR->getValueType().getAsString() << '\'';
+    range = TOR->getExpr()->getSourceRange();
+  }
+  else {
+    llvm_unreachable("Invalid region in ReturnStackAddressChecker.");
+  } 
+  
+  return range;
+}
+
+void StackAddrEscapeChecker::EmitStackError(CheckerContext &C, const MemRegion *R,
+                                          const Expr *RetE) const {
+  ExplodedNode *N = C.generateSink();
+
+  if (!N)
+    return;
+
+  if (!BT_returnstack)
+   BT_returnstack.reset(
+                 new BuiltinBug("Return of address to stack-allocated memory"));
+
+  // Generate a report for this bug.
+  SmallString<512> buf;
+  llvm::raw_svector_ostream os(buf);
+  SourceRange range = GenName(os, R, C.getSourceManager());
+  os << " returned to caller";
+  BugReport *report = new BugReport(*BT_returnstack, os.str(), N);
+  report->addRange(RetE->getSourceRange());
+  if (range.isValid())
+    report->addRange(range);
+
+  C.EmitReport(report);
+}
+
+void StackAddrEscapeChecker::checkPreStmt(const ReturnStmt *RS,
+                                          CheckerContext &C) const {
+  
+  const Expr *RetE = RS->getRetValue();
+  if (!RetE)
+    return;
+ 
+  SVal V = C.getState()->getSVal(RetE, C.getLocationContext());
+  const MemRegion *R = V.getAsRegion();
+
+  if (!R)
+    return;
+  
+  const StackSpaceRegion *SS =
+    dyn_cast_or_null<StackSpaceRegion>(R->getMemorySpace());
+    
+  if (!SS)
+    return;
+
+  // Return stack memory in an ancestor stack frame is fine.
+  const StackFrameContext *SFC = SS->getStackFrame();
+  if (SFC != C.getLocationContext()->getCurrentStackFrame())
+    return;
+
+  // Automatic reference counting automatically copies blocks.
+  if (C.getASTContext().getLangOpts().ObjCAutoRefCount &&
+      isa<BlockDataRegion>(R))
+    return;
+
+  EmitStackError(C, R, RetE);
+}
+
+void StackAddrEscapeChecker::checkEndPath(CheckerContext &Ctx) const {
+  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 *CurSFC;
+  public:
+    SmallVector<std::pair<const MemRegion*, const MemRegion*>, 10> V;
+
+    CallBack(CheckerContext &CC) :
+      Ctx(CC),
+      CurSFC(CC.getLocationContext()->getCurrentStackFrame())
+    {}
+    
+    bool HandleBinding(StoreManager &SMgr, Store store,
+                       const MemRegion *region, SVal val) {
+      
+      if (!isa<GlobalsSpaceRegion>(region->getMemorySpace()))
+        return true;
+      
+      const MemRegion *vR = val.getAsRegion();
+      if (!vR)
+        return true;
+        
+      // Under automated retain release, it is okay to assign a block
+      // directly to a global variable.
+      if (Ctx.getASTContext().getLangOpts().ObjCAutoRefCount &&
+          isa<BlockDataRegion>(vR))
+        return true;
+
+      if (const StackSpaceRegion *SSR = 
+          dyn_cast<StackSpaceRegion>(vR->getMemorySpace())) {
+        // If the global variable holds a location in the current stack frame,
+        // record the binding to emit a warning.
+        if (SSR->getStackFrame() == CurSFC)
+          V.push_back(std::make_pair(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.addTransition(state);
+  if (!N)
+    return;
+
+  if (!BT_stackleak)
+    BT_stackleak.reset(
+      new BuiltinBug("Stack address stored into global variable",
+                     "Stack address was saved into a global variable. "
+                     "This is dangerous because the address will become "
+                     "invalid after returning from the function"));
+  
+  for (unsigned i = 0, e = cb.V.size(); i != e; ++i) {
+    // Generate a report for this bug.
+    SmallString<512> buf;
+    llvm::raw_svector_ostream os(buf);
+    SourceRange range = GenName(os, cb.V[i].second,
+                                Ctx.getSourceManager());
+    os << " is still referred to by the global variable '";
+    const VarRegion *VR = cast<VarRegion>(cb.V[i].first->getBaseRegion());
+    os << *VR->getDecl()
+       << "' upon returning to the caller.  This will be a dangling reference";
+    BugReport *report = new BugReport(*BT_stackleak, os.str(), N);
+    if (range.isValid())
+      report->addRange(range);
+
+    Ctx.EmitReport(report);
+  }
+}
+
+void ento::registerStackAddrEscapeChecker(CheckerManager &mgr) {
+  mgr.registerChecker<StackAddrEscapeChecker>();
+}