[PATCH] D139604: [PATCH] Github Issue: Create a check that warns about using %p printf specifier #43453

[Gianni Crivello via Phabricator via cfe-commits]

giannicrivello updated this revision to Diff 481154.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D139604/new/

https://reviews.llvm.org/D139604

Files:
  clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
  clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp


Index: clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
+++ clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
@@ -11,11 +11,12 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
 #include "clang/Basic/TargetInfo.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 "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
@@ -59,9 +60,11 @@
 
 };
 
-class UnixAPIPortabilityChecker : public Checker< check::PreStmt<CallExpr> > {
+class UnixAPIPortabilityChecker
+    : public Checker<check::PreStmt<CallExpr>, check::PostCall> {
 public:
   void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
+  void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
 
 private:
   mutable std::unique_ptr<BugType> BT_mallocZero;
@@ -493,6 +496,41 @@
     CheckVallocZero(C, CE);
 }
 
+void UnixAPIPortabilityChecker::checkPostCall(const CallEvent &Call,
+                                              CheckerContext &C) const {
+
+  auto State = C.getState();
+
+  const IdentifierInfo *II = Call.getCalleeIdentifier();
+  if (!II)
+    return;
+  if (!II->isStr("printf"))
+    return;
+
+  if (!BT_mallocZero)
+    BT_mallocZero.reset(new BugType(this, "Call to printf", "Example checker"));
+
+  for (unsigned int i = 0; i < Call.getNumArgs(); i++) {
+    const auto *Arg = Call.getArgExpr(i);
+    if (!Arg)
+      return;
+    const auto *LC = C.getLocationContext();
+    auto Val = State->getSVal(Arg, LC);
+    if (Val.isZeroConstant()) {
+      ExplodedNode *N = C.generateErrorNode();
+
+      // Further better the diagnostic message by adding a bug report visitor
+      auto Report = std::make_unique<PathSensitiveBugReport>(
+          *BT_mallocZero,
+          "Passing a null pointer to printf() is implementation dependant. "
+          "Portability warning.",
+          N);
+      Report->addRange(Arg->getSourceRange());
+      C.emitReport(std::move(Report));
+    }
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // Registration.
 //===----------------------------------------------------------------------===//
Index: clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
===================================================================
--- clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
+++ clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
@@ -1667,7 +1667,7 @@
 def UnixAPIPortabilityChecker : Checker<"UnixAPI">,
   HelpText<"Finds implementation-defined behavior in UNIX/Posix functions">,
   Documentation<NotDocumented>;
-
+  
 } // end optin.portability
 
 //===----------------------------------------------------------------------===//


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