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[cfi] Don't emit checks for disabled CFI kinds.

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In the cross-DSO CFI mode clang emits __cfi_check_fail that handles
errors triggered from other modules with targets in the current
module. With this change, __cfi_check_fail will handle errors for
CFI kinds that are not enabled in the current module as if they
have the trapping behaviour (-fsanitize-trap=...).

This fixes a bug where some combinations of -fsanitize* flags may
result in a link failure due to a missing sanitizer runtime library
for the diagnostic calls in __cfi_check_fail.

llvm-svn: 263578
This commit is contained in:
Evgeniy Stepanov 2016-03-15 20:19:29 +00:00
parent ef156c6701
commit 02279ed12d
3 changed files with 79 additions and 9 deletions
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15
clang/lib/CodeGen/CGExpr.cpp
View File

@ -2479,16 +2479,12 @@ void CodeGenFunction::EmitCheck(
assert(JointCond);
CheckRecoverableKind RecoverKind = getRecoverableKind(Checked[0].second);
// In cross-DSO CFI mode this code is used to generate __cfi_check_fail, which
// includes all checks, even those that are not in SanOpts.
assert(CGM.getCodeGenOpts().SanitizeCfiCrossDso ||
SanOpts.has(Checked[0].second));
assert(SanOpts.has(Checked[0].second));
#ifndef NDEBUG
for (int i = 1, n = Checked.size(); i < n; ++i) {
assert(RecoverKind == getRecoverableKind(Checked[i].second) &&
"All recoverable kinds in a single check must be same!");
assert(CGM.getCodeGenOpts().SanitizeCfiCrossDso ||
SanOpts.has(Checked[i].second));
assert(SanOpts.has(Checked[i].second));
}
#endif
@ -2670,8 +2666,11 @@ void CodeGenFunction::EmitCfiCheckFail() {
SanitizerMask Mask = CheckKindMaskPair.second;
llvm::Value *Cond =
Builder.CreateICmpNE(CheckKind, llvm::ConstantInt::get(Int8Ty, Kind));
EmitCheck(std::make_pair(Cond, Mask), "cfi_check_fail", {},
{Data, Addr, ValidVtable});
if (CGM.getLangOpts().Sanitize.has(Mask))
EmitCheck(std::make_pair(Cond, Mask), "cfi_check_fail", {},
{Data, Addr, ValidVtable});
else
EmitTrapCheck(Cond);
}
FinishFunction();

3
clang/test/CodeGen/cfi-check-fail.c
View File

@ -1,4 +1,5 @@
// RUN: %clang_cc1 -triple x86_64-unknown-linux -O0 -fsanitize=cfi-icall -fsanitize-cfi-cross-dso \
// RUN: %clang_cc1 -triple x86_64-unknown-linux -O0 -fsanitize-cfi-cross-dso \
// RUN: -fsanitize=cfi-icall,cfi-nvcall,cfi-vcall,cfi-unrelated-cast,cfi-derived-cast \
// RUN: -fsanitize-trap=cfi-icall,cfi-nvcall -fsanitize-recover=cfi-vcall,cfi-unrelated-cast \
// RUN: -emit-llvm -o - %s | FileCheck %s

70
clang/test/CodeGen/cfi-check-fail2.c Normal file
View File

@ -0,0 +1,70 @@
// __cfi_check_fail codegen when not all CFI checkers are enabled.
// RUN: %clang_cc1 -triple x86_64-unknown-linux -O0 -fsanitize-cfi-cross-dso \
// RUN: -fsanitize=cfi-vcall \
// RUN: -emit-llvm -o - %s | FileCheck %s
void caller(void (*f)()) {
f();
}
// CHECK: define weak_odr hidden void @__cfi_check_fail(i8*, i8*) {
// CHECK: store i8* %0, i8** %[[ALLOCA0:.*]], align 8
// CHECK: store i8* %1, i8** %[[ALLOCA1:.*]], align 8
// CHECK: %[[DATA:.*]] = load i8*, i8** %[[ALLOCA0]], align 8
// CHECK: %[[ADDR:.*]] = load i8*, i8** %[[ALLOCA1]], align 8
// CHECK: %[[ICMP_NOT_NULL:.*]] = icmp ne i8* %[[DATA]], null
// CHECK: br i1 %[[ICMP_NOT_NULL]], label %[[CONT0:.*]], label %[[TRAP:.*]],
// CHECK: [[TRAP]]:
// CHECK-NEXT: call void @llvm.trap()
// CHECK-NEXT: unreachable
// CHECK: [[CONT0]]:
// CHECK: %[[A:.*]] = bitcast i8* %[[DATA]] to { i8, { i8*, i32, i32 }, i8* }*
// CHECK: %[[KINDPTR:.*]] = getelementptr {{.*}} %[[A]], i32 0, i32 0
// CHECK: %[[KIND:.*]] = load i8, i8* %[[KINDPTR]], align 4
// CHECK: %[[VTVALID0:.*]] = call i1 @llvm.bitset.test(i8* %[[ADDR]], metadata !"all-vtables")
// CHECK: %[[VTVALID:.*]] = zext i1 %[[VTVALID0]] to i64
// CHECK: %[[NOT_0:.*]] = icmp ne i8 %[[KIND]], 0
// CHECK: br i1 %[[NOT_0]], label %[[CONT1:.*]], label %[[HANDLE0:.*]], !prof
// CHECK: [[HANDLE0]]:
// CHECK: %[[DATA0:.*]] = ptrtoint i8* %[[DATA]] to i64,
// CHECK: %[[ADDR0:.*]] = ptrtoint i8* %[[ADDR]] to i64,
// CHECK: call void @__ubsan_handle_cfi_check_fail_abort(i64 %[[DATA0]], i64 %[[ADDR0]], i64 %[[VTVALID]])
// CHECK: unreachable
// CHECK: [[CONT1]]:
// CHECK: %[[NOT_1:.*]] = icmp ne i8 %[[KIND]], 1
// CHECK: br i1 %[[NOT_1]], label %[[CONT2:.*]], label %[[HANDLE1:.*]], !nosanitize
// CHECK: [[HANDLE1]]:
// CHECK-NEXT: call void @llvm.trap()
// CHECK-NEXT: unreachable
// CHECK: [[CONT2]]:
// CHECK: %[[NOT_2:.*]] = icmp ne i8 %[[KIND]], 2
// CHECK: br i1 %[[NOT_2]], label %[[CONT3:.*]], label %[[HANDLE2:.*]], !nosanitize
// CHECK: [[HANDLE2]]:
// CHECK-NEXT: call void @llvm.trap()
// CHECK-NEXT: unreachable
// CHECK: [[CONT3]]:
// CHECK: %[[NOT_3:.*]] = icmp ne i8 %[[KIND]], 3
// CHECK: br i1 %[[NOT_3]], label %[[CONT4:.*]], label %[[HANDLE3:.*]], !nosanitize
// CHECK: [[HANDLE3]]:
// CHECK-NEXT: call void @llvm.trap()
// CHECK-NEXT: unreachable
// CHECK: [[CONT4]]:
// CHECK: %[[NOT_4:.*]] = icmp ne i8 %[[KIND]], 4
// CHECK: br i1 %[[NOT_4]], label %[[CONT5:.*]], label %[[HANDLE4:.*]], !nosanitize
// CHECK: [[HANDLE4]]:
// CHECK-NEXT: call void @llvm.trap()
// CHECK-NEXT: unreachable
// CHECK: [[CONT5]]:
// CHECK: ret void