[clang] Adding optin.taint.TaintedDiv checker (PR #106389)
Daniel Krupp via cfe-commits
cfe-commits at lists.llvm.org
Wed Aug 28 08:50:06 PDT 2024
https://github.com/dkrupp updated https://github.com/llvm/llvm-project/pull/106389
>From ccc5da054903568fbd317d5c773251ed84f8f087 Mon Sep 17 00:00:00 2001
From: Daniel Krupp <daniel.krupp at ericsson.com>
Date: Wed, 28 Aug 2024 15:32:35 +0200
Subject: [PATCH 1/2] Adding optin.taint.TaintedDiv checker
Tainted division operation is separated out from the core.DivideZero
checker into the optional optin.taint.TaintedDiv checker.
The checker warns when the denominator in a division operation
is an attacker controlled value.
---
clang/docs/analyzer/checkers.rst | 28 +++++++++++
.../clang/StaticAnalyzer/Checkers/Checkers.td | 6 +++
.../StaticAnalyzer/Core/CheckerManager.h | 5 ++
.../Checkers/DivZeroChecker.cpp | 46 +++++++++++++++++--
.../test/Analysis/taint-diagnostic-visitor.c | 2 +-
clang/test/Analysis/taint-generic.c | 3 ++
6 files changed, 84 insertions(+), 6 deletions(-)
diff --git a/clang/docs/analyzer/checkers.rst b/clang/docs/analyzer/checkers.rst
index 89a1018e14c0e6..fab060302310bb 100644
--- a/clang/docs/analyzer/checkers.rst
+++ b/clang/docs/analyzer/checkers.rst
@@ -1053,6 +1053,34 @@ by explicitly marking the ``size`` parameter as sanitized. See the
delete[] ptr;
}
+.. _optin-taint-TaintedDiv:
+
+optin.taint.TaintedDiv (C, C++, ObjC)
+"""""""""""""""""""""""""""""""""""""
+This checker warns when the denominator in a division
+operation is a tainted (potentially attacker controlled) value.
+If the attacker can set the denominator to 0, a runtime error can
+be triggered. The checker warns if the analyzer cannot prove
+that the denominator is not 0 and it is a tainted value.
+This warning is more pessimistic than the :ref:`core-DivideZero` checker
+which warns only when it can prove that the denominator is 0.
+
+.. code-block:: c
+
+ int vulnerable(int n) {
+ size_t size = 0;
+ scanf("%zu", &size);
+ return n/size; // warn: Division by a tainted value, possibly zero
+ }
+
+ int not_vulnerable(void) {
+ size_t size = 0;
+ scanf("%zu", &size);
+ if (!size)
+ return 0;
+ return n/size; // no warning
+ }
+
.. _security-checkers:
security
diff --git a/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td b/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
index fb4114619ac3d3..5a9afa0f15f5a0 100644
--- a/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
+++ b/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
@@ -1710,6 +1710,12 @@ def TaintedAllocChecker: Checker<"TaintedAlloc">,
Dependencies<[DynamicMemoryModeling, TaintPropagationChecker]>,
Documentation<HasDocumentation>;
+def TaintedDivChecker: Checker<"TaintedDiv">,
+ HelpText<"Check for divisions, where the denominator "
+ "might be 0 as it is a tainted (attacker controlled) value.">,
+ Dependencies<[TaintPropagationChecker]>,
+ Documentation<HasDocumentation>;
+
} // end "optin.taint"
//===----------------------------------------------------------------------===//
diff --git a/clang/include/clang/StaticAnalyzer/Core/CheckerManager.h b/clang/include/clang/StaticAnalyzer/Core/CheckerManager.h
index ad25d18f280700..e47c0c310eb8e7 100644
--- a/clang/include/clang/StaticAnalyzer/Core/CheckerManager.h
+++ b/clang/include/clang/StaticAnalyzer/Core/CheckerManager.h
@@ -223,6 +223,11 @@ class CheckerManager {
return static_cast<CHECKER *>(CheckerTags[tag]);
}
+ template <typename CHECKER> bool isRegisteredChecker() {
+ CheckerTag tag = getTag<CHECKER>();
+ return (CheckerTags.count(tag) != 0);
+ }
+
//===----------------------------------------------------------------------===//
// Functions for running checkers for AST traversing.
//===----------------------------------------------------------------------===//
diff --git a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
index 5496f087447fbe..89aac24d7576e5 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
@@ -26,8 +26,6 @@ using namespace taint;
namespace {
class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
- const BugType BT{this, "Division by zero"};
- const BugType TaintBT{this, "Division by zero", categories::TaintedData};
void reportBug(StringRef Msg, ProgramStateRef StateZero,
CheckerContext &C) const;
void reportTaintBug(StringRef Msg, ProgramStateRef StateZero,
@@ -35,6 +33,12 @@ class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
llvm::ArrayRef<SymbolRef> TaintedSyms) const;
public:
+ /// This checker class implements multiple user facing checker
+ enum CheckKind { CK_DivZeroChecker, CK_TaintedDivChecker, CK_NumCheckKinds };
+ bool ChecksEnabled[CK_NumCheckKinds] = {false};
+ CheckerNameRef CheckNames[CK_NumCheckKinds];
+ mutable std::unique_ptr<BugType> BugTypes[CK_NumCheckKinds];
+
void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
};
} // end anonymous namespace
@@ -48,8 +52,14 @@ static const Expr *getDenomExpr(const ExplodedNode *N) {
void DivZeroChecker::reportBug(StringRef Msg, ProgramStateRef StateZero,
CheckerContext &C) const {
+ if (!ChecksEnabled[CK_DivZeroChecker])
+ return;
+ if (!BugTypes[CK_DivZeroChecker])
+ BugTypes[CK_DivZeroChecker].reset(
+ new BugType(CheckNames[CK_DivZeroChecker], "Division by zero"));
if (ExplodedNode *N = C.generateErrorNode(StateZero)) {
- auto R = std::make_unique<PathSensitiveBugReport>(BT, Msg, N);
+ auto R = std::make_unique<PathSensitiveBugReport>(
+ *BugTypes[CK_DivZeroChecker], Msg, N);
bugreporter::trackExpressionValue(N, getDenomExpr(N), *R);
C.emitReport(std::move(R));
}
@@ -58,8 +68,15 @@ void DivZeroChecker::reportBug(StringRef Msg, ProgramStateRef StateZero,
void DivZeroChecker::reportTaintBug(
StringRef Msg, ProgramStateRef StateZero, CheckerContext &C,
llvm::ArrayRef<SymbolRef> TaintedSyms) const {
+ if (!ChecksEnabled[CK_TaintedDivChecker])
+ return;
+ if (!BugTypes[CK_TaintedDivChecker])
+ BugTypes[CK_TaintedDivChecker].reset(
+ new BugType(CheckNames[CK_TaintedDivChecker], "Division by zero",
+ categories::TaintedData));
if (ExplodedNode *N = C.generateErrorNode(StateZero)) {
- auto R = std::make_unique<PathSensitiveBugReport>(TaintBT, Msg, N);
+ auto R = std::make_unique<PathSensitiveBugReport>(
+ *BugTypes[CK_TaintedDivChecker], Msg, N);
bugreporter::trackExpressionValue(N, getDenomExpr(N), *R);
for (auto Sym : TaintedSyms)
R->markInteresting(Sym);
@@ -113,9 +130,28 @@ void DivZeroChecker::checkPreStmt(const BinaryOperator *B,
}
void ento::registerDivZeroChecker(CheckerManager &mgr) {
- mgr.registerChecker<DivZeroChecker>();
+ DivZeroChecker *checker = mgr.registerChecker<DivZeroChecker>();
+ ;
+ checker->ChecksEnabled[DivZeroChecker::CK_DivZeroChecker] = true;
+ checker->CheckNames[DivZeroChecker::CK_DivZeroChecker] =
+ mgr.getCurrentCheckerName();
}
bool ento::shouldRegisterDivZeroChecker(const CheckerManager &mgr) {
return true;
}
+
+void ento::registerTaintedDivChecker(CheckerManager &mgr) {
+ DivZeroChecker *checker;
+ if (!mgr.isRegisteredChecker<DivZeroChecker>())
+ checker = mgr.registerChecker<DivZeroChecker>();
+ else
+ checker = mgr.getChecker<DivZeroChecker>();
+ checker->ChecksEnabled[DivZeroChecker::CK_TaintedDivChecker] = true;
+ checker->CheckNames[DivZeroChecker::CK_TaintedDivChecker] =
+ mgr.getCurrentCheckerName();
+}
+
+bool ento::shouldRegisterTaintedDivChecker(const CheckerManager &mgr) {
+ return true;
+}
diff --git a/clang/test/Analysis/taint-diagnostic-visitor.c b/clang/test/Analysis/taint-diagnostic-visitor.c
index f51423646e8aec..11820003e8c4d8 100644
--- a/clang/test/Analysis/taint-diagnostic-visitor.c
+++ b/clang/test/Analysis/taint-diagnostic-visitor.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -analyze -analyzer-checker=alpha.security.taint,core,alpha.security.ArrayBoundV2,optin.taint.TaintedAlloc -analyzer-output=text -verify %s
+// RUN: %clang_cc1 -analyze -analyzer-checker=alpha.security.taint,core,alpha.security.ArrayBoundV2,optin.taint.TaintedAlloc,optin.taint.TaintedDiv -analyzer-output=text -verify %s
// This file is for testing enhanced diagnostics produced by the GenericTaintChecker
diff --git a/clang/test/Analysis/taint-generic.c b/clang/test/Analysis/taint-generic.c
index 1c139312734bca..e74e1a48ee40bb 100644
--- a/clang/test/Analysis/taint-generic.c
+++ b/clang/test/Analysis/taint-generic.c
@@ -1,6 +1,7 @@
// RUN: %clang_analyze_cc1 -Wno-format-security -Wno-pointer-to-int-cast \
// RUN: -Wno-incompatible-library-redeclaration -verify %s \
// RUN: -analyzer-checker=alpha.security.taint \
+// RUN: -analyzer-checker=optin.taint.TaintedDiv \
// RUN: -analyzer-checker=core \
// RUN: -analyzer-checker=alpha.security.ArrayBoundV2 \
// RUN: -analyzer-checker=debug.ExprInspection \
@@ -11,6 +12,7 @@
// RUN: -Wno-incompatible-library-redeclaration -verify %s \
// RUN: -DFILE_IS_STRUCT \
// RUN: -analyzer-checker=alpha.security.taint \
+// RUN: -analyzer-checker=optin.taint.TaintedDiv \
// RUN: -analyzer-checker=core \
// RUN: -analyzer-checker=alpha.security.ArrayBoundV2 \
// RUN: -analyzer-checker=debug.ExprInspection \
@@ -20,6 +22,7 @@
// RUN: not %clang_analyze_cc1 -Wno-pointer-to-int-cast \
// RUN: -Wno-incompatible-library-redeclaration -verify %s \
// RUN: -analyzer-checker=alpha.security.taint \
+// RUN: -analyzer-checker=optin.taint.TaintedDiv \
// RUN: -analyzer-checker=debug.ExprInspection \
// RUN: -analyzer-config \
// RUN: alpha.security.taint.TaintPropagation:Config=justguessit \
>From 5b52f2853358402c33c2f6b5e271ff6c4b383a15 Mon Sep 17 00:00:00 2001
From: Daniel Krupp <daniel.krupp at ericsson.com>
Date: Wed, 28 Aug 2024 17:49:50 +0200
Subject: [PATCH 2/2] formatting fix
---
clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
index 89aac24d7576e5..da160f13301413 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
@@ -25,7 +25,7 @@ using namespace ento;
using namespace taint;
namespace {
-class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
+class DivZeroChecker : public Checker<check::PreStmt<BinaryOperator>> {
void reportBug(StringRef Msg, ProgramStateRef StateZero,
CheckerContext &C) const;
void reportTaintBug(StringRef Msg, ProgramStateRef StateZero,
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