[clang] 09b8dbf - [analyzer] Add optin.taint.TaintedDiv checker (#106389)
via cfe-commits
cfe-commits at lists.llvm.org
Tue Oct 1 02:33:10 PDT 2024
Author: Daniel Krupp
Date: 2024-10-01T11:33:06+02:00
New Revision: 09b8dbfa80d62e64efb09bd166324270c96badf9
URL: https://github.com/llvm/llvm-project/commit/09b8dbfa80d62e64efb09bd166324270c96badf9
DIFF: https://github.com/llvm/llvm-project/commit/09b8dbfa80d62e64efb09bd166324270c96badf9.diff
LOG: [analyzer] Add optin.taint.TaintedDiv checker (#106389)
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.
Added:
clang/test/Analysis/divzero-tainted-div-difference.c
Modified:
clang/docs/analyzer/checkers.rst
clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
clang/include/clang/StaticAnalyzer/Core/CheckerManager.h
clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
clang/test/Analysis/taint-diagnostic-visitor.c
clang/test/Analysis/taint-generic.c
Removed:
################################################################################
diff --git a/clang/docs/analyzer/checkers.rst b/clang/docs/analyzer/checkers.rst
index a22bda189dd295..81264428c72ed1 100644
--- a/clang/docs/analyzer/checkers.rst
+++ b/clang/docs/analyzer/checkers.rst
@@ -1288,6 +1288,34 @@ 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 when the denominator is a tainted
+value and the analyzer cannot prove that it is not 0. 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(int n) {
+ 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 6bc389f9da265f..349040c15eeb83 100644
--- a/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
+++ b/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td
@@ -1703,6 +1703,12 @@ def TaintedAllocChecker: Checker<"TaintedAlloc">,
Dependencies<[DynamicMemoryModeling, TaintPropagationChecker]>,
Documentation<HasDocumentation>;
+def TaintedDivChecker: Checker<"TaintedDiv">,
+ HelpText<"Check for divisions where the denominator is tainted "
+ "(attacker controlled) and might be 0.">,
+ 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 24c5b66fd58220..de40b96614dbc9 100644
--- a/clang/include/clang/StaticAnalyzer/Core/CheckerManager.h
+++ b/clang/include/clang/StaticAnalyzer/Core/CheckerManager.h
@@ -221,6 +221,10 @@ class CheckerManager {
return static_cast<CHECKER *>(CheckerTags[tag]);
}
+ template <typename CHECKER> bool isRegisteredChecker() {
+ return CheckerTags.contains(getTag<CHECKER>());
+ }
+
//===----------------------------------------------------------------------===//
// 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..7c8b44eb05942a 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
@@ -25,9 +25,7 @@ using namespace ento;
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};
+class DivZeroChecker : public Checker<check::PreStmt<BinaryOperator>> {
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 several user facing checkers
+ enum CheckKind { CK_DivideZero, 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_DivideZero])
+ return;
+ if (!BugTypes[CK_DivideZero])
+ BugTypes[CK_DivideZero].reset(
+ new BugType(CheckNames[CK_DivideZero], "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_DivideZero],
+ 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 (ExplodedNode *N = C.generateErrorNode(StateZero)) {
- auto R = std::make_unique<PathSensitiveBugReport>(TaintBT, Msg, N);
+ 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.generateNonFatalErrorNode(StateZero)) {
+ auto R = std::make_unique<PathSensitiveBugReport>(
+ *BugTypes[CK_TaintedDivChecker], Msg, N);
bugreporter::trackExpressionValue(N, getDenomExpr(N), *R);
for (auto Sym : TaintedSyms)
R->markInteresting(Sym);
@@ -101,8 +118,8 @@ void DivZeroChecker::checkPreStmt(const BinaryOperator *B,
if ((stateNotZero && stateZero)) {
std::vector<SymbolRef> taintedSyms = getTaintedSymbols(C.getState(), *DV);
if (!taintedSyms.empty()) {
- reportTaintBug("Division by a tainted value, possibly zero", stateZero, C,
- taintedSyms);
+ reportTaintBug("Division by a tainted value, possibly zero", stateNotZero,
+ C, taintedSyms);
return;
}
}
@@ -113,9 +130,27 @@ void DivZeroChecker::checkPreStmt(const BinaryOperator *B,
}
void ento::registerDivZeroChecker(CheckerManager &mgr) {
- mgr.registerChecker<DivZeroChecker>();
+ DivZeroChecker *checker = mgr.registerChecker<DivZeroChecker>();
+ checker->ChecksEnabled[DivZeroChecker::CK_DivideZero] = true;
+ checker->CheckNames[DivZeroChecker::CK_DivideZero] =
+ 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/divzero-tainted-div-
diff erence.c b/clang/test/Analysis/divzero-tainted-div-
diff erence.c
new file mode 100644
index 00000000000000..28486ccdf7e4fe
--- /dev/null
+++ b/clang/test/Analysis/divzero-tainted-div-
diff erence.c
@@ -0,0 +1,34 @@
+// RUN: %clang_analyze_cc1 -Wno-format-security -Wno-pointer-to-int-cast \
+// RUN: -Wno-incompatible-library-redeclaration -verify=normaldiv %s \
+// RUN: -analyzer-checker=optin.taint.GenericTaint \
+// RUN: -analyzer-checker=core
+
+// RUN: %clang_analyze_cc1 -Wno-format-security -Wno-pointer-to-int-cast \
+// RUN: -Wno-incompatible-library-redeclaration -verify=tainteddiv %s \
+// RUN: -analyzer-checker=optin.taint.GenericTaint \
+// RUN: -analyzer-checker=optin.taint.TaintedDiv
+
+int getchar(void);
+
+
+//If we are sure that we divide by zero
+//we emit a divide by zero warning
+int testDivZero(void) {
+ int x = getchar(); // taint source
+ if (!x)
+ return 5 / x; // normaldiv-warning{{Division by zero}}
+ return 8;
+}
+
+// The attacker provided value might be 0
+int testDivZero2(void) {
+ int x = getchar(); // taint source
+ return 5 / x; // tainteddiv-warning{{Division by a tainted value}}
+}
+
+int testDivZero3(void) {
+ int x = getchar(); // taint source
+ if (!x)
+ return 0;
+ return 5 / x; // no warning
+}
diff --git a/clang/test/Analysis/taint-diagnostic-visitor.c b/clang/test/Analysis/taint-diagnostic-visitor.c
index 526c04c3607775..223df9951fd6b9 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=optin.taint,core,alpha.security.ArrayBoundV2,optin.taint.TaintedAlloc -analyzer-output=text -verify %s
+// RUN: %clang_cc1 -analyze -analyzer-checker=optin.taint,core,alpha.security.ArrayBoundV2 -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 a5cfdd9db11579..ad5a99fe8b3a35 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=optin.taint.GenericTaint \
+// RUN: -analyzer-checker=optin.taint.TaintedDiv \
// RUN: -analyzer-checker=core \
// RUN: -analyzer-checker=alpha.security.ArrayBoundV2 \
// RUN: -analyzer-checker=debug.ExprInspection \
@@ -11,16 +12,15 @@
// RUN: -Wno-incompatible-library-redeclaration -verify %s \
// RUN: -DFILE_IS_STRUCT \
// RUN: -analyzer-checker=optin.taint.GenericTaint \
+// RUN: -analyzer-checker=optin.taint.TaintedDiv \
// RUN: -analyzer-checker=core \
// RUN: -analyzer-checker=alpha.security.ArrayBoundV2 \
// RUN: -analyzer-checker=debug.ExprInspection \
// RUN: -analyzer-config \
// RUN: optin.taint.TaintPropagation:Config=%S/Inputs/taint-generic-config.yaml
-// RUN: not %clang_analyze_cc1 -Wno-pointer-to-int-cast \
-// RUN: -Wno-incompatible-library-redeclaration -verify %s \
+// RUN: not %clang_analyze_cc1 -verify %s \
// RUN: -analyzer-checker=optin.taint.GenericTaint \
-// RUN: -analyzer-checker=debug.ExprInspection \
// RUN: -analyzer-config \
// RUN: optin.taint.TaintPropagation:Config=justguessit \
// RUN: 2>&1 | FileCheck %s -check-prefix=CHECK-INVALID-FILE
@@ -30,10 +30,8 @@
// CHECK-INVALID-FILE-SAME: that expects a valid filename instead of
// CHECK-INVALID-FILE-SAME: 'justguessit'
-// RUN: not %clang_analyze_cc1 -Wno-incompatible-library-redeclaration \
-// RUN: -verify %s \
+// RUN: not %clang_analyze_cc1 -verify %s \
// RUN: -analyzer-checker=optin.taint.GenericTaint \
-// RUN: -analyzer-checker=debug.ExprInspection \
// RUN: -analyzer-config \
// RUN: optin.taint.TaintPropagation:Config=%S/Inputs/taint-generic-config-ill-formed.yaml \
// RUN: 2>&1 | FileCheck -DMSG=%errc_EINVAL %s -check-prefix=CHECK-ILL-FORMED
@@ -42,10 +40,8 @@
// CHECK-ILL-FORMED-SAME: 'optin.taint.TaintPropagation:Config',
// CHECK-ILL-FORMED-SAME: that expects a valid yaml file: [[MSG]]
-// RUN: not %clang_analyze_cc1 -Wno-incompatible-library-redeclaration \
-// RUN: -verify %s \
+// RUN: not %clang_analyze_cc1 -verify %s \
// RUN: -analyzer-checker=optin.taint.GenericTaint \
-// RUN: -analyzer-checker=debug.ExprInspection \
// RUN: -analyzer-config \
// RUN: optin.taint.TaintPropagation:Config=%S/Inputs/taint-generic-config-invalid-arg.yaml \
// RUN: 2>&1 | FileCheck %s -check-prefix=CHECK-INVALID-ARG
@@ -408,6 +404,14 @@ int testDivByZero(void) {
return 5/x; // expected-warning {{Division by a tainted value, possibly zero}}
}
+int testTaintedDivFP(void) {
+ int x;
+ scanf("%d", &x);
+ if (!x)
+ return 0;
+ return 5/x; // x cannot be 0, so no tainted warning either
+}
+
// Zero-sized VLAs.
void testTaintedVLASize(void) {
int x;
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