r289290 - [ubsan] Treat ObjC's BOOL as if its range is always {0, 1}

[Vedant Kumar via cfe-commits]

Author: vedantk
Date: Fri Dec  9 17:48:18 2016
New Revision: 289290

URL: http://llvm.org/viewvc/llvm-project?rev=289290&view=rev
Log:
[ubsan] Treat ObjC's BOOL as if its range is always {0, 1}

On some Apple platforms, the ObjC BOOL type is defined as a signed char.
When performing instrumentation for -fsanitize=bool, we'd like to treat
the range of BOOL like it's always {0, 1}. While we can't change clang's
IRGen for char-backed BOOL's due to ABI compatibility concerns, we can
teach ubsan to catch potential abuses of this type.

rdar://problem/29502773

Differential Revision: https://reviews.llvm.org/D27607

Added:
    cfe/trunk/test/CodeGenObjC/ubsan-bool.m
Modified:
    cfe/trunk/lib/CodeGen/CGExpr.cpp

Modified: cfe/trunk/lib/CodeGen/CGExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExpr.cpp?rev=289290&r1=289289&r2=289290&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExpr.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExpr.cpp Fri Dec  9 17:48:18 2016
@@ -24,6 +24,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/DeclObjC.h"
+#include "clang/AST/NSAPI.h"
 #include "clang/Frontend/CodeGenOptions.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringExtras.h"
@@ -1219,11 +1220,10 @@ static bool hasBooleanRepresentation(Qua
 
 static bool getRangeForType(CodeGenFunction &CGF, QualType Ty,
                             llvm::APInt &Min, llvm::APInt &End,
-                            bool StrictEnums) {
+                            bool StrictEnums, bool IsBool) {
   const EnumType *ET = Ty->getAs<EnumType>();
   bool IsRegularCPlusPlusEnum = CGF.getLangOpts().CPlusPlus && StrictEnums &&
                                 ET && !ET->getDecl()->isFixed();
-  bool IsBool = hasBooleanRepresentation(Ty);
   if (!IsBool && !IsRegularCPlusPlusEnum)
     return false;
 
@@ -1253,8 +1253,8 @@ static bool getRangeForType(CodeGenFunct
 
 llvm::MDNode *CodeGenFunction::getRangeForLoadFromType(QualType Ty) {
   llvm::APInt Min, End;
-  if (!getRangeForType(*this, Ty, Min, End,
-                       CGM.getCodeGenOpts().StrictEnums))
+  if (!getRangeForType(*this, Ty, Min, End, CGM.getCodeGenOpts().StrictEnums,
+                       hasBooleanRepresentation(Ty)))
     return nullptr;
 
   llvm::MDBuilder MDHelper(getLLVMContext());
@@ -1313,14 +1313,15 @@ llvm::Value *CodeGenFunction::EmitLoadOf
                                       false /*ConvertTypeToTag*/);
   }
 
-  bool NeedsBoolCheck =
-      SanOpts.has(SanitizerKind::Bool) && hasBooleanRepresentation(Ty);
+  bool IsBool = hasBooleanRepresentation(Ty) ||
+                NSAPI(CGM.getContext()).isObjCBOOLType(Ty);
+  bool NeedsBoolCheck = SanOpts.has(SanitizerKind::Bool) && IsBool;
   bool NeedsEnumCheck =
       SanOpts.has(SanitizerKind::Enum) && Ty->getAs<EnumType>();
   if (NeedsBoolCheck || NeedsEnumCheck) {
     SanitizerScope SanScope(this);
     llvm::APInt Min, End;
-    if (getRangeForType(*this, Ty, Min, End, true)) {
+    if (getRangeForType(*this, Ty, Min, End, /*StrictEnums=*/true, IsBool)) {
       --End;
       llvm::Value *Check;
       if (!Min)

Added: cfe/trunk/test/CodeGenObjC/ubsan-bool.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/ubsan-bool.m?rev=289290&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenObjC/ubsan-bool.m (added)
+++ cfe/trunk/test/CodeGenObjC/ubsan-bool.m Fri Dec  9 17:48:18 2016
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -x objective-c -emit-llvm -triple x86_64-apple-macosx10.10.0 -fsanitize=bool %s -o - | FileCheck %s -check-prefixes=SHARED,OBJC
+// RUN: %clang_cc1 -x objective-c++ -emit-llvm -triple x86_64-apple-macosx10.10.0 -fsanitize=bool %s -o - | FileCheck %s -check-prefixes=SHARED,OBJC
+// RUN: %clang_cc1 -x c -emit-llvm -triple x86_64-apple-macosx10.10.0 -fsanitize=bool %s -o - | FileCheck %s -check-prefixes=SHARED,C
+
+typedef signed char BOOL;
+
+// SHARED-LABEL: f1
+BOOL f1() {
+  // OBJC: call void @__ubsan_handle_load_invalid_value
+  // C-NOT: call void @__ubsan_handle_load_invalid_value
+  BOOL a = 2;
+  return a + 1;
+}