Hi rsmith,
This patch adds a runtime check verifying that functions
annotated with "returns_nonnull" attribute do in fact return nonnull pointers.
It is based on suggestion by Jakub Jelinek:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140623/223693.html.
I'm sending a follow-up email to that thread to discuss design issues.
http://reviews.llvm.org/D4849
Files:
projects/compiler-rt/lib/ubsan/ubsan_handlers.cc
projects/compiler-rt/lib/ubsan/ubsan_handlers.h
projects/compiler-rt/test/ubsan/TestCases/Misc/nonnull.cpp
tools/clang/include/clang/Basic/Sanitizers.def
tools/clang/lib/CodeGen/CGCall.cpp
tools/clang/test/CodeGen/catch-undef-behavior.c
tools/clang/test/Driver/fsanitize.c
Index: tools/clang/lib/CodeGen/CGCall.cpp
===================================================================
--- tools/clang/lib/CodeGen/CGCall.cpp
+++ tools/clang/lib/CodeGen/CGCall.cpp
@@ -1998,7 +1998,25 @@
llvm_unreachable("Invalid ABI kind for return argument");
}
- llvm::Instruction *Ret = RV ? Builder.CreateRet(RV) : Builder.CreateRetVoid();
+ llvm::Instruction *Ret;
+ if (RV) {
+ if (SanOpts->ReturnsNonnull &&
+ CurGD.getDecl()->hasAttr<ReturnsNonNullAttr>() &&
+ RV->getType()->getPointerAddressSpace() == 0) {
+ SanitizerScope SanScope(this);
+ llvm::Value *Cond =
+ Builder.CreateICmpNE(RV, llvm::Constant::getNullValue(RV->getType()));
+ llvm::Constant *StaticData[] = {
+ EmitCheckSourceLocation(EndLoc)
+ };
+ EmitCheck(Cond, "nonnull_return", StaticData, ArrayRef<llvm::Value *>(),
+ CRK_Recoverable);
+ }
+ Ret = Builder.CreateRet(RV);
+ } else {
+ Ret = Builder.CreateRetVoid();
+ }
+
if (!RetDbgLoc.isUnknown())
Ret->setDebugLoc(RetDbgLoc);
}
Index: tools/clang/test/Driver/fsanitize.c
===================================================================
--- tools/clang/test/Driver/fsanitize.c
+++ tools/clang/test/Driver/fsanitize.c
@@ -1,22 +1,22 @@
// RUN: %clang -target x86_64-linux-gnu -fsanitize=undefined-trap -fsanitize-undefined-trap-on-error %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UNDEFINED-TRAP
// RUN: %clang -target x86_64-linux-gnu -fsanitize-undefined-trap-on-error -fsanitize=undefined-trap %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UNDEFINED-TRAP
-// CHECK-UNDEFINED-TRAP: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|shift|unreachable|return|vla-bound|alignment|null|object-size|float-cast-overflow|array-bounds|enum|bool),?){14}"}}
+// CHECK-UNDEFINED-TRAP: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|shift|unreachable|return|vla-bound|alignment|null|object-size|float-cast-overflow|array-bounds|enum|bool|returns-nonnull),?){15}"}}
// CHECK-UNDEFINED-TRAP: "-fsanitize-undefined-trap-on-error"
// RUN: %clang -target x86_64-linux-gnu -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UNDEFINED
-// CHECK-UNDEFINED: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|function|shift|unreachable|return|vla-bound|alignment|null|vptr|object-size|float-cast-overflow|array-bounds|enum|bool),?){16}"}}
+// CHECK-UNDEFINED: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|function|shift|unreachable|return|vla-bound|alignment|null|vptr|object-size|float-cast-overflow|array-bounds|enum|bool|returns-nonnull),?){17}"}}
// RUN: %clang -target x86_64-apple-darwin10 -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UNDEFINED-DARWIN
-// CHECK-UNDEFINED-DARWIN: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|shift|unreachable|return|vla-bound|alignment|null|vptr|object-size|float-cast-overflow|array-bounds|enum|bool),?){15}"}}
+// CHECK-UNDEFINED-DARWIN: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|shift|unreachable|return|vla-bound|alignment|null|vptr|object-size|float-cast-overflow|array-bounds|enum|bool|returns-nonnull),?){16}"}}
// RUN: %clang -target x86_64-linux-gnu -fsanitize=integer %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-INTEGER
// CHECK-INTEGER: "-fsanitize={{((signed-integer-overflow|unsigned-integer-overflow|integer-divide-by-zero|shift),?){4}"}}
// RUN: %clang -fsanitize=bounds -### -fsyntax-only %s 2>&1 | FileCheck %s --check-prefix=CHECK-BOUNDS
// CHECK-BOUNDS: "-fsanitize={{((array-bounds|local-bounds),?){2}"}}
// RUN: %clang -target x86_64-linux-gnu -fsanitize=thread,undefined -fno-sanitize=thread -fno-sanitize=float-cast-overflow,vptr,bool,enum %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-PARTIAL-UNDEFINED
-// CHECK-PARTIAL-UNDEFINED: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|function|shift|unreachable|return|vla-bound|alignment|null|object-size|array-bounds),?){12}"}}
+// CHECK-PARTIAL-UNDEFINED: "-fsanitize={{((signed-integer-overflow|integer-divide-by-zero|float-divide-by-zero|function|shift|unreachable|return|vla-bound|alignment|null|object-size|array-bounds|returns-nonnull),?){13}"}}
// RUN: %clang -target x86_64-linux-gnu -fsanitize=undefined -fsanitize-undefined-trap-on-error %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UNDEFINED-TRAP-ON-ERROR-UNDEF
// CHECK-UNDEFINED-TRAP-ON-ERROR-UNDEF: '-fsanitize=undefined' not allowed with '-fsanitize-undefined-trap-on-error'
Index: tools/clang/test/CodeGen/catch-undef-behavior.c
===================================================================
--- tools/clang/test/CodeGen/catch-undef-behavior.c
+++ tools/clang/test/CodeGen/catch-undef-behavior.c
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
-// RUN: %clang_cc1 -fsanitize-undefined-trap-on-error -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-TRAP
+// RUN: %clang_cc1 -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool,returns-nonnull -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
+// RUN: %clang_cc1 -fsanitize-undefined-trap-on-error -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool,returns-nonnull -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-TRAP
// RUN: %clang_cc1 -fsanitize=null -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-NULL
// RUN: %clang_cc1 -fsanitize=signed-integer-overflow -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-OVERFLOW
@@ -432,6 +432,20 @@
return *p;
}
+// CHECK-LABEL: @ret_nonnull
+__attribute__((returns_nonnull))
+int *ret_nonnull(int *a) {
+ // CHECK: [[OK:%.*]] = icmp ne i32* {{.*}}, null
+ // CHECK: br i1 [[OK]]
+ // CHECK: call void @__ubsan_handle_nonnull_return
+
+ // CHECK-TRAP: [[OK:%.*]] = icmp ne i32* {{.*}}, null
+ // CHECK-TRAP: br i1 [[OK]]
+ // CHECK-TRAP: call void @llvm.trap() [[NR_NUW]]
+ // CHECK-TRAP: unreachable
+ return a;
+}
+
// CHECK: ![[WEIGHT_MD]] = metadata !{metadata !"branch_weights", i32 1048575, i32 1}
// CHECK-TRAP: attributes [[NR_NUW]] = { noreturn nounwind }
Index: tools/clang/include/clang/Basic/Sanitizers.def
===================================================================
--- tools/clang/include/clang/Basic/Sanitizers.def
+++ tools/clang/include/clang/Basic/Sanitizers.def
@@ -62,6 +62,7 @@
SANITIZER("null", Null)
SANITIZER("object-size", ObjectSize)
SANITIZER("return", Return)
+SANITIZER("returns-nonnull", ReturnsNonnull)
SANITIZER("shift", Shift)
SANITIZER("signed-integer-overflow", SignedIntegerOverflow)
SANITIZER("unreachable", Unreachable)
@@ -78,19 +79,19 @@
// ABI or address space layout implications, and only catch undefined behavior.
SANITIZER_GROUP("undefined", Undefined,
Alignment | Bool | ArrayBounds | Enum | FloatCastOverflow |
- FloatDivideByZero | Function | IntegerDivideByZero | Null |
- ObjectSize | Return | Shift | SignedIntegerOverflow |
- Unreachable | VLABound | Vptr)
+ FloatDivideByZero | Function | IntegerDivideByZero | Null |
+ ObjectSize | Return | ReturnsNonnull | Shift |
+ SignedIntegerOverflow | Unreachable | VLABound | Vptr)
// -fsanitize=undefined-trap includes
// all sanitizers included by -fsanitize=undefined, except those that require
// runtime support. This group is generally used in conjunction with the
// -fsanitize-undefined-trap-on-error flag.
SANITIZER_GROUP("undefined-trap", UndefinedTrap,
Alignment | Bool | ArrayBounds | Enum | FloatCastOverflow |
- FloatDivideByZero | IntegerDivideByZero | Null | ObjectSize |
- Return | Shift | SignedIntegerOverflow | Unreachable |
- VLABound)
+ FloatDivideByZero | IntegerDivideByZero | Null |
+ ObjectSize | Return | ReturnsNonnull | Shift |
+ SignedIntegerOverflow | Unreachable | VLABound)
SANITIZER_GROUP("integer", Integer,
SignedIntegerOverflow | UnsignedIntegerOverflow | Shift |
Index: projects/compiler-rt/lib/ubsan/ubsan_handlers.cc
===================================================================
--- projects/compiler-rt/lib/ubsan/ubsan_handlers.cc
+++ projects/compiler-rt/lib/ubsan/ubsan_handlers.cc
@@ -308,3 +308,21 @@
FunctionTypeMismatchData *Data, ValueHandle Function) {
handleFunctionTypeMismatch(Data, Function, true);
}
+
+static void handleNonnullReturn(NonNullReturnData *Data, bool Abort) {
+ SourceLocation Loc = Data->Loc.acquire();
+ if (Loc.isDisabled())
+ return;
+
+ ScopedReport R(Abort);
+
+ Diag(Loc, DL_Error, "null return value where non-null is required");
+}
+
+void __ubsan::__ubsan_handle_nonnull_return(NonNullReturnData *Data) {
+ handleNonnullReturn(Data, false);
+}
+
+void __ubsan::__ubsan_handle_nonnull_return_abort(NonNullReturnData *Data) {
+ handleNonnullReturn(Data, true);
+}
Index: projects/compiler-rt/lib/ubsan/ubsan_handlers.h
===================================================================
--- projects/compiler-rt/lib/ubsan/ubsan_handlers.h
+++ projects/compiler-rt/lib/ubsan/ubsan_handlers.h
@@ -121,6 +121,13 @@
FunctionTypeMismatchData *Data,
ValueHandle Val)
+struct NonNullReturnData {
+ SourceLocation Loc;
+};
+
+/// \brief Handle returning null from function with returns_nonnull attribute.
+RECOVERABLE(nonnull_return, NonNullReturnData *Data)
+
}
#endif // UBSAN_HANDLERS_H
Index: projects/compiler-rt/test/ubsan/TestCases/Misc/nonnull.cpp
===================================================================
--- /dev/null
+++ projects/compiler-rt/test/ubsan/TestCases/Misc/nonnull.cpp
@@ -0,0 +1,13 @@
+// RUN: %clangxx -fsanitize=returns-nonnull %s -O3 -o %t
+// RUN: %run %t foo
+// RUN: %run %t 2>&1 | FileCheck %s
+
+__attribute__((returns_nonnull))
+char *foo(char *a) {
+ return a;
+ // CHECK: nonnull.cpp:[[@LINE+1]]:1: runtime error: null return value where non-null is required
+}
+
+int main(int argc, char **argv) {
+ return foo(argv[1]) == 0;
+}
_______________________________________________
cfe-commits mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
