1 files changed, 96 insertions, 0 deletions
diff --git a/lib/Checker/VLASizeChecker.cpp b/lib/Checker/VLASizeChecker.cpp
new file mode 100644
index 0000000..51ad1e2
--- /dev/null
+++ b/lib/Checker/VLASizeChecker.cpp
@@ -0,0 +1,96 @@
+//=== VLASizeChecker.cpp - Undefined dereference checker --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines VLASizeChecker, a builtin check in GRExprEngine that 
+// performs checks for declaration of VLA of undefined or zero size.
+//
+//===----------------------------------------------------------------------===//
+
+#include "GRExprEngineInternalChecks.h"
+#include "clang/Checker/PathSensitive/CheckerVisitor.h"
+#include "clang/Checker/PathSensitive/GRExprEngine.h"
+#include "clang/Checker/BugReporter/BugReporter.h"
+
+using namespace clang;
+
+namespace {
+class VLASizeChecker : public CheckerVisitor<VLASizeChecker> {
+  BugType *BT_zero;
+  BugType *BT_undef;
+  
+public:
+  VLASizeChecker() : BT_zero(0), BT_undef(0) {}
+  static void *getTag() { static int tag = 0; return &tag; }
+  void PreVisitDeclStmt(CheckerContext &C, const DeclStmt *DS);
+};
+} // end anonymous namespace
+
+void clang::RegisterVLASizeChecker(GRExprEngine &Eng) {
+  Eng.registerCheck(new VLASizeChecker());
+}
+
+void VLASizeChecker::PreVisitDeclStmt(CheckerContext &C, const DeclStmt *DS) {
+  if (!DS->isSingleDecl())
+    return;
+  
+  const VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
+  if (!VD)
+    return;
+  
+  const VariableArrayType *VLA
+    = C.getASTContext().getAsVariableArrayType(VD->getType());
+  if (!VLA)
+    return;
+
+  // FIXME: Handle multi-dimensional VLAs.
+  const Expr* SE = VLA->getSizeExpr();
+  const GRState *state = C.getState();
+  SVal sizeV = state->getSVal(SE);
+
+  if (sizeV.isUndef()) {
+    // Generate an error node.
+    ExplodedNode *N = C.GenerateSink();
+    if (!N)
+      return;
+    
+    if (!BT_undef)
+      BT_undef = new BuiltinBug("Declared variable-length array (VLA) uses a "
+                                "garbage value as its size");
+
+    EnhancedBugReport *report =
+      new EnhancedBugReport(*BT_undef, BT_undef->getName(), N);
+    report->addRange(SE->getSourceRange());
+    report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, SE);
+    C.EmitReport(report);
+    return;
+  }
+  
+  // Check if the size is zero.
+  DefinedOrUnknownSVal sizeD = cast<DefinedOrUnknownSVal>(sizeV);
+
+  const GRState *stateNotZero, *stateZero;
+  llvm::tie(stateNotZero, stateZero) = state->Assume(sizeD);
+
+  if (stateZero && !stateNotZero) {
+    ExplodedNode* N = C.GenerateSink(stateZero);
+    if (!BT_zero)
+      BT_zero = new BuiltinBug("Declared variable-length array (VLA) has zero "
+                               "size");
+
+    EnhancedBugReport *report =
+      new EnhancedBugReport(*BT_zero, BT_zero->getName(), N);
+    report->addRange(SE->getSourceRange());
+    report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, SE);
+    C.EmitReport(report);
+    return;
+  }
+ 
+  // From this point on, assume that the size is not zero.
+  C.addTransition(stateNotZero);
+}