Split libAnalysis into two libraries: libAnalysis and libChecker.

(1) libAnalysis is a generic analysis library that can be used by
    Sema.  It defines the CFG, basic dataflow analysis primitives, and
    inexpensive flow-sensitive analyses (e.g. LiveVariables).

(2) libChecker contains the guts of the static analyzer, incuding the
    path-sensitive analysis engine and domain-specific checks.

Now any clients that want to use the frontend to build their own tools
don't need to link in the entire static analyzer.

This change exposes various obvious cleanups that can be made to the
layout of files and headers in libChecker.  More changes pending.  :)

This change also exposed a layering violation between AnalysisContext
and MemRegion.  BlockInvocationContext shouldn't explicitly know about
BlockDataRegions.  For now I've removed the BlockDataRegion* from
BlockInvocationContext (removing context-sensitivity; although this
wasn't used yet).  We need to have a better way to extend
BlockInvocationContext (and any LocationContext) to add
context-sensitivty.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94406 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 97 insertions, 0 deletions

diff --git a/lib/Checker/ReturnPointerRangeChecker.cpp b/lib/Checker/ReturnPointerRangeChecker.cpp
new file mode 100644
index 0000000000..0a19254528
--- /dev/null
+++ b/lib/Checker/ReturnPointerRangeChecker.cpp
@@ -0,0 +1,97 @@
+//== ReturnPointerRangeChecker.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 ReturnPointerRangeChecker, which is a path-sensitive check
+// which looks for an out-of-bound pointer being returned to callers.
+//
+//===----------------------------------------------------------------------===//
+
+#include "GRExprEngineInternalChecks.h"
+#include "clang/Checker/PathSensitive/GRExprEngine.h"
+#include "clang/Checker/PathSensitive/BugReporter.h"
+#include "clang/Checker/PathSensitive/CheckerVisitor.h"
+
+using namespace clang;
+
+namespace {
+class ReturnPointerRangeChecker : 
+    public CheckerVisitor<ReturnPointerRangeChecker> {      
+  BuiltinBug *BT;
+public:
+    ReturnPointerRangeChecker() : BT(0) {}
+    static void *getTag();
+    void PreVisitReturnStmt(CheckerContext &C, const ReturnStmt *RS);
+};
+}
+
+void clang::RegisterReturnPointerRangeChecker(GRExprEngine &Eng) {
+  Eng.registerCheck(new ReturnPointerRangeChecker());
+}
+
+void *ReturnPointerRangeChecker::getTag() {
+  static int x = 0; return &x;
+}
+
+void ReturnPointerRangeChecker::PreVisitReturnStmt(CheckerContext &C,
+                                                   const ReturnStmt *RS) {
+  const GRState *state = C.getState();
+
+  const Expr *RetE = RS->getRetValue();
+  if (!RetE)
+    return;
+ 
+  SVal V = state->getSVal(RetE);
+  const MemRegion *R = V.getAsRegion();
+  if (!R)
+    return;
+
+  R = R->StripCasts();
+  if (!R)
+    return;
+
+  const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(R);
+  if (!ER)
+    return;
+
+  DefinedOrUnknownSVal &Idx = cast<DefinedOrUnknownSVal>(ER->getIndex());
+
+  // FIXME: All of this out-of-bounds checking should eventually be refactored
+  // into a common place.
+
+  DefinedOrUnknownSVal NumElements
+    = C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(),
+                                           ER->getValueType(C.getASTContext()));
+
+  const GRState *StInBound = state->AssumeInBound(Idx, NumElements, true);
+  const GRState *StOutBound = state->AssumeInBound(Idx, NumElements, false);
+  if (StOutBound && !StInBound) {
+    ExplodedNode *N = C.GenerateSink(StOutBound);
+
+    if (!N)
+      return;
+  
+    // FIXME: This bug correspond to CWE-466.  Eventually we should have bug
+    // types explicitly reference such exploit categories (when applicable).
+    if (!BT)
+      BT = new BuiltinBug("Return of pointer value outside of expected range",
+           "Returned pointer value points outside the original object "
+           "(potential 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.
+    RangedBugReport *report = 
+      new RangedBugReport(*BT, BT->getDescription(), N);
+
+    report->addRange(RetE->getSourceRange());
+    C.EmitReport(report);
+  }
+}