[CodeGen][CFI] Generalize transparent union parameters

clang/lib/CodeGen/CGExpr.cpp

@@ -6496,11 +6496,8 @@ RValue CodeGenFunction::EmitCall(QualType CalleeType,
     SanitizerDebugLocation SanScope(this, {CheckOrdinal}, CheckHandler);
     EmitSanitizerStatReport(llvm::SanStat_CFI_ICall);
 
-    llvm::Metadata *MD;
-    if (CGM.getCodeGenOpts().SanitizeCfiICallGeneralizePointers)
-      MD = CGM.CreateMetadataIdentifierGeneralized(QualType(FnType, 0));
-    else
-      MD = CGM.CreateMetadataIdentifierForType(QualType(FnType, 0));
+    llvm::Metadata *MD =
+        CGM.CreateMetadataIdentifierForFnType(QualType(FnType, 0));
 
     llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
 

clang/lib/CodeGen/CodeGenModule.cpp

@@ -2339,12 +2339,28 @@ llvm::ConstantInt *CodeGenModule::CreateCrossDsoCfiTypeId(llvm::Metadata *MD) {
   return llvm::ConstantInt::get(Int64Ty, llvm::MD5Hash(MDS->getString()));
 }
 
+static QualType GeneralizeTransparentUnion(QualType Ty) {
+  const RecordType *UT = Ty->getAsUnionType();
+  if (!UT)
+    return Ty;
+  const RecordDecl *UD = UT->getOriginalDecl()->getDefinitionOrSelf();
+  if (!UD->hasAttr<TransparentUnionAttr>())
+    return Ty;
+  for (const auto *it : UD->fields()) {
+    return it->getType();
+  }
+  return Ty;
+}
+
 // Generalize pointer types to a void pointer with the qualifiers of the
 // originally pointed-to type, e.g. 'const char *' and 'char * const *'
 // generalize to 'const void *' while 'char *' and 'const char **' generalize to
 // 'void *'.
-static QualType GeneralizeType(ASTContext &Ctx, QualType Ty) {
-  if (!Ty->isPointerType())
+static QualType GeneralizeType(ASTContext &Ctx, QualType Ty,
+                               bool GeneralizePointers) {
+  Ty = GeneralizeTransparentUnion(Ty);
+
+  if (!GeneralizePointers || !Ty->isPointerType())
     return Ty;
 
   return Ctx.getPointerType(
@@ -2353,26 +2369,29 @@ static QualType GeneralizeType(ASTContext &Ctx, QualType Ty) {
 }
 
 // Apply type generalization to a FunctionType's return and argument types
-static QualType GeneralizeFunctionType(ASTContext &Ctx, QualType Ty) {
+static QualType GeneralizeFunctionType(ASTContext &Ctx, QualType Ty,
+                                       bool GeneralizePointers) {
   if (auto *FnType = Ty->getAs<FunctionProtoType>()) {
     SmallVector<QualType, 8> GeneralizedParams;
     for (auto &Param : FnType->param_types())
-      GeneralizedParams.push_back(GeneralizeType(Ctx, Param));
+      GeneralizedParams.push_back(
+          GeneralizeType(Ctx, Param, GeneralizePointers));
 
-    return Ctx.getFunctionType(GeneralizeType(Ctx, FnType->getReturnType()),
-                               GeneralizedParams, FnType->getExtProtoInfo());
+    return Ctx.getFunctionType(
+        GeneralizeType(Ctx, FnType->getReturnType(), GeneralizePointers),
+        GeneralizedParams, FnType->getExtProtoInfo());
   }
 
   if (auto *FnType = Ty->getAs<FunctionNoProtoType>())
     return Ctx.getFunctionNoProtoType(
-        GeneralizeType(Ctx, FnType->getReturnType()));
+        GeneralizeType(Ctx, FnType->getReturnType(), GeneralizePointers));
 
   llvm_unreachable("Encountered unknown FunctionType");
 }
 
 llvm::ConstantInt *CodeGenModule::CreateKCFITypeId(QualType T, StringRef Salt) {
-  if (getCodeGenOpts().SanitizeCfiICallGeneralizePointers)
-    T = GeneralizeFunctionType(getContext(), T);
+  T = GeneralizeFunctionType(
+      getContext(), T, getCodeGenOpts().SanitizeCfiICallGeneralizePointers);
   if (auto *FnType = T->getAs<FunctionProtoType>())
     T = getContext().getFunctionType(
         FnType->getReturnType(), FnType->getParamTypes(),
@@ -3041,9 +3060,14 @@ void CodeGenModule::createFunctionTypeMetadataForIcall(const FunctionDecl *FD,
   if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic())
     return;
 
-  llvm::Metadata *MD = CreateMetadataIdentifierForType(FD->getType());
+  QualType FnType = GeneralizeFunctionType(getContext(), FD->getType(),
+                                           /*GeneralizePointers=*/false);
+  llvm::Metadata *MD = CreateMetadataIdentifierForType(FnType);
   F->addTypeMetadata(0, MD);
-  F->addTypeMetadata(0, CreateMetadataIdentifierGeneralized(FD->getType()));
+
+  QualType GenPtrFnType = GeneralizeFunctionType(getContext(), FD->getType(),
+                                                 /*GeneralizePointers=*/true);
+  F->addTypeMetadata(0, CreateMetadataIdentifierGeneralized(GenPtrFnType));
 
   // Emit a hash-based bit set entry for cross-DSO calls.
   if (CodeGenOpts.SanitizeCfiCrossDso)
@@ -7934,6 +7958,15 @@ CodeGenModule::CreateMetadataIdentifierImpl(QualType T, MetadataTypeMap &Map,
   return InternalId;
 }
 
+llvm::Metadata *CodeGenModule::CreateMetadataIdentifierForFnType(QualType T) {
+  assert(isa<FunctionType>(T));
+  T = GeneralizeFunctionType(
+      getContext(), T, getCodeGenOpts().SanitizeCfiICallGeneralizePointers);
+  if (getCodeGenOpts().SanitizeCfiICallGeneralizePointers)
+    return CreateMetadataIdentifierGeneralized(T);
+  return CreateMetadataIdentifierForType(T);
+}
+
 llvm::Metadata *CodeGenModule::CreateMetadataIdentifierForType(QualType T) {
   return CreateMetadataIdentifierImpl(T, MetadataIdMap, "");
 }
@@ -7944,8 +7977,8 @@ CodeGenModule::CreateMetadataIdentifierForVirtualMemPtrType(QualType T) {
 }
 
 llvm::Metadata *CodeGenModule::CreateMetadataIdentifierGeneralized(QualType T) {
-  return CreateMetadataIdentifierImpl(GeneralizeFunctionType(getContext(), T),
-                                      GeneralizedMetadataIdMap, ".generalized");
+  return CreateMetadataIdentifierImpl(T, GeneralizedMetadataIdMap,
+                                      ".generalized");
 }
 
 /// Returns whether this module needs the "all-vtables" type identifier.

clang/lib/CodeGen/CodeGenModule.h

@@ -1623,6 +1623,9 @@ class CodeGenModule : public CodeGenTypeCache {
   /// Generate a KCFI type identifier for T.
   llvm::ConstantInt *CreateKCFITypeId(QualType T, StringRef Salt);
 
+  /// Create a metadata identifier for the given function type.
+  llvm::Metadata *CreateMetadataIdentifierForFnType(QualType T);
+
   /// Create a metadata identifier for the given type. This may either be an
   /// MDString (for external identifiers) or a distinct unnamed MDNode (for
   /// internal identifiers).

clang/test/CodeGen/cfi-icall-generalize.c

@@ -15,5 +15,21 @@ void g(int** (*fp)(const char *, const char **)) {
   fp(0, 0);
 }
 
+union Union {
+  char *c;
+  long *n;
+} __attribute__((transparent_union));
+
+// CHECK: define{{.*}} void @uni({{.*}} !type [[TYPE2:![0-9]+]] !type [[TYPE2_GENERALIZED:![0-9]+]]
+void uni(void (*fn)(union Union), union Union arg1) {
+  // UNGENERALIZED: call i1 @llvm.type.test(ptr {{.*}}, metadata !"_ZTSFvPcE")
+  // GENERALIZED: call i1 @llvm.type.test(ptr {{.*}}, metadata !"_ZTSFvPvE.generalized")
+    fn(arg1);
+}
+
 // CHECK: [[TYPE]] = !{i64 0, !"_ZTSFPPiPKcPS2_E"}
 // CHECK: [[TYPE_GENERALIZED]] = !{i64 0, !"_ZTSFPvPKvS_E.generalized"}
+
+// CHECK: [[TYPE2]] = !{i64 0, !"_ZTSFvPFv5UnionEPcE"}
+// CHECK: [[TYPE2_GENERALIZED]] = !{i64 0, !"_ZTSFvPvS_E.generalized"}
+

clang/test/CodeGen/cfi-icall-normalize2.c

@@ -24,6 +24,20 @@ void baz(void (*fn)(int, int, int), int arg1, int arg2, int arg3) {
     fn(arg1, arg2, arg3);
 }
 
+union Union {
+  char *c;
+  long *n;
+} __attribute__((transparent_union));
+
+void uni(void (*fn)(union Union), union Union arg1) {
+    // CHECK-LABEL: define{{.*}}uni
+    // CHECK-SAME: {{.*}}!type ![[TYPE4:[0-9]+]] !type !{{[0-9]+}}
+    // CHECK: call i1 @llvm.type.test({{i8\*|ptr}} {{%f|%0}}, metadata !"_ZTSFvPu2i8E.normalized")
+    fn(arg1);
+}
+
 // CHECK: ![[TYPE1]] = !{i64 0, !"_ZTSFvPFvu3i32ES_E.normalized"}
 // CHECK: ![[TYPE2]] = !{i64 0, !"_ZTSFvPFvu3i32S_ES_S_E.normalized"}
 // CHECK: ![[TYPE3]] = !{i64 0, !"_ZTSFvPFvu3i32S_S_ES_S_S_E.normalized"}
+// CHECK: ![[TYPE4]] = !{i64 0, !"_ZTSFvPFv5UnionEPu2i8E.normalized"}
+

clang/test/CodeGen/kcfi-generalize.c

@@ -26,8 +26,23 @@ void g(int** (*fp)(const char *, const char **)) {
   fp(0, 0);
 }
 
+union Union {
+  char *c;
+  long *n;
+} __attribute__((transparent_union));
+
+// CHECK: define{{.*}} void @uni({{.*}} !kcfi_type [[TYPE4:![0-9]+]]
+void uni(void (*fn)(union Union), union Union arg1) {
+  // UNGENERALIZED: call {{.*}} [ "kcfi"(i32 -587217045) ]
+  // GENERALIZED: call {{.*}} [ "kcfi"(i32 2139530422) ]
+    fn(arg1);
+}
+
 // UNGENERALIZED: [[TYPE]] = !{i32 1296635908}
 // GENERALIZED: [[TYPE]] = !{i32 -49168686}
 
 // UNGENERALIZED: [[TYPE3]] = !{i32 874141567}
 // GENERALIZED: [[TYPE3]] = !{i32 954385378}
+
+// UNGENERALIZED: [[TYPE4]] = !{i32 -1619636625}
+// GENERALIZED: [[TYPE4]] = !{i32 -125078496}

clang/test/CodeGen/kcfi-normalize.c

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers -o - %s | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers -x c++ -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers -o - %s | FileCheck %s --check-prefixes=CHECK,C
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers -x c++ -o - %s | FileCheck %s --check-prefixes=CHECK,CPP
 #if !__has_feature(kcfi)
 #error Missing kcfi?
 #endif
@@ -28,7 +28,22 @@ void baz(void (*fn)(int, int, int), int arg1, int arg2, int arg3) {
     fn(arg1, arg2, arg3);
 }
 
+union Union {
+  char *c;
+  long *n;
+} __attribute__((transparent_union));
+
+void uni(void (*fn)(union Union), union Union arg1) {
+    // CHECK-LABEL: define{{.*}}uni
+    // CHECK-SAME: {{.*}}!kcfi_type ![[TYPE4:[0-9]+]]
+    // C: call void %0(ptr %1) [ "kcfi"(i32 1819770848) ]
+    // CPP: call void %0(ptr %1) [ "kcfi"(i32 -1430221633) ]
+    fn(arg1);
+}
+
 // CHECK: ![[#]] = !{i32 4, !"cfi-normalize-integers", i32 1}
 // CHECK: ![[TYPE1]] = !{i32 -1143117868}
 // CHECK: ![[TYPE2]] = !{i32 -460921415}
 // CHECK: ![[TYPE3]] = !{i32 -333839615}
+// C: ![[TYPE4]] = !{i32 -650530463}
+// CPP: ![[TYPE4]] = !{i32 1766237188}