[clang] [compiler-rt] [clang][UBSan] Add implicit conversion check for bitfields (PR #75481)
Axel Lundberg via cfe-commits
cfe-commits at lists.llvm.org
Sun Mar 10 14:22:41 PDT 2024
https://github.com/Zonotora updated https://github.com/llvm/llvm-project/pull/75481
>From cd64144a4cf18adba1494871bfd9da1b0bf0a489 Mon Sep 17 00:00:00 2001
From: Zonotora <Zonotora at hotmail.com>
Date: Sat, 16 Dec 2023 19:33:21 +0100
Subject: [PATCH 1/3] [clang] Extract negativity check lambda to function
---
clang/lib/CodeGen/CGExprScalar.cpp | 41 ++++++++++++++----------------
1 file changed, 19 insertions(+), 22 deletions(-)
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 8536570087ad0f..74d94259572dc2 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -1103,6 +1103,21 @@ void ScalarExprEmitter::EmitIntegerTruncationCheck(Value *Src, QualType SrcType,
{Src, Dst});
}
+static llvm::Value *EmitIsNegativeTestHelper(Value *V, QualType VType,
+ const char *Name,
+ CGBuilderTy &Builder) {
+ bool VSigned = VType->isSignedIntegerOrEnumerationType();
+ llvm::Type *VTy = V->getType();
+ if (!VSigned) {
+ // If the value is unsigned, then it is never negative.
+ return llvm::ConstantInt::getFalse(VTy->getContext());
+ }
+ llvm::Constant *Zero = llvm::ConstantInt::get(VTy, 0);
+ return Builder.CreateICmp(llvm::ICmpInst::ICMP_SLT, V, Zero,
+ llvm::Twine(Name) + "." + V->getName() +
+ ".negativitycheck");
+};
+
// Should be called within CodeGenFunction::SanitizerScope RAII scope.
// Returns 'i1 false' when the conversion Src -> Dst changed the sign.
static std::pair<ScalarExprEmitter::ImplicitConversionCheckKind,
@@ -1127,30 +1142,12 @@ EmitIntegerSignChangeCheckHelper(Value *Src, QualType SrcType, Value *Dst,
assert(((SrcBits != DstBits) || (SrcSigned != DstSigned)) &&
"either the widths should be different, or the signednesses.");
- // NOTE: zero value is considered to be non-negative.
- auto EmitIsNegativeTest = [&Builder](Value *V, QualType VType,
- const char *Name) -> Value * {
- // Is this value a signed type?
- bool VSigned = VType->isSignedIntegerOrEnumerationType();
- llvm::Type *VTy = V->getType();
- if (!VSigned) {
- // If the value is unsigned, then it is never negative.
- // FIXME: can we encounter non-scalar VTy here?
- return llvm::ConstantInt::getFalse(VTy->getContext());
- }
- // Get the zero of the same type with which we will be comparing.
- llvm::Constant *Zero = llvm::ConstantInt::get(VTy, 0);
- // %V.isnegative = icmp slt %V, 0
- // I.e is %V *strictly* less than zero, does it have negative value?
- return Builder.CreateICmp(llvm::ICmpInst::ICMP_SLT, V, Zero,
- llvm::Twine(Name) + "." + V->getName() +
- ".negativitycheck");
- };
-
// 1. Was the old Value negative?
- llvm::Value *SrcIsNegative = EmitIsNegativeTest(Src, SrcType, "src");
+ llvm::Value *SrcIsNegative =
+ EmitIsNegativeTestHelper(Src, SrcType, "src", Builder);
// 2. Is the new Value negative?
- llvm::Value *DstIsNegative = EmitIsNegativeTest(Dst, DstType, "dst");
+ llvm::Value *DstIsNegative =
+ EmitIsNegativeTestHelper(Dst, DstType, "dst", Builder);
// 3. Now, was the 'negativity status' preserved during the conversion?
// NOTE: conversion from negative to zero is considered to change the sign.
// (We want to get 'false' when the conversion changed the sign)
>From e5914b0519efa0d70c429f2b08b326f863df4fbe Mon Sep 17 00:00:00 2001
From: Zonotora <Zonotora at hotmail.com>
Date: Sat, 16 Dec 2023 19:36:04 +0100
Subject: [PATCH 2/3] [clang][UBSan] Add implicit conversion check for
bitfields
This patch implements the implicit truncation and implicit
sign change checks for bitfields.
---
clang/docs/ReleaseNotes.rst | 7 +
clang/docs/UndefinedBehaviorSanitizer.rst | 19 +-
clang/include/clang/Basic/Sanitizers.def | 20 +-
clang/lib/CodeGen/CGExpr.cpp | 45 +++-
clang/lib/CodeGen/CGExprScalar.cpp | 224 +++++++++++++++++-
clang/lib/CodeGen/CodeGenFunction.h | 12 +
.../test/CodeGen/ubsan-bitfield-conversion.c | 61 +++++
compiler-rt/lib/ubsan/ubsan_handlers.cpp | 27 ++-
compiler-rt/lib/ubsan/ubsan_handlers.h | 1 +
9 files changed, 378 insertions(+), 38 deletions(-)
create mode 100644 clang/test/CodeGen/ubsan-bitfield-conversion.c
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3b89d5a8720785..7a8135077a2bc2 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -173,6 +173,10 @@ Non-comprehensive list of changes in this release
New Compiler Flags
------------------
+- ``-fsanitize=implicit-bitfield-conversion`` checks implicit truncation and
+ sign change.
+- ``-fsanitize=implicit-integer-conversion`` a group that replaces the previous
+ group ``-fsanitize=implicit-conversion``.
- ``-Wmissing-designated-field-initializers``, grouped under ``-Wmissing-field-initializers``.
This diagnostic can be disabled to make ``-Wmissing-field-initializers`` behave
@@ -183,6 +187,9 @@ Deprecated Compiler Flags
Modified Compiler Flags
-----------------------
+- ``-fsanitize=implicit-conversion`` is now a group for both
+ ``-fsanitize=implicit-integer-conversion`` and
+ ``-fsanitize=implicit-bitfield-conversion``.
Removed Compiler Flags
-------------------------
diff --git a/clang/docs/UndefinedBehaviorSanitizer.rst b/clang/docs/UndefinedBehaviorSanitizer.rst
index 8f58c92bd2a163..531d56e313826c 100644
--- a/clang/docs/UndefinedBehaviorSanitizer.rst
+++ b/clang/docs/UndefinedBehaviorSanitizer.rst
@@ -148,6 +148,11 @@ Available checks are:
Issues caught by this sanitizer are not undefined behavior,
but are often unintentional.
- ``-fsanitize=integer-divide-by-zero``: Integer division by zero.
+ - ``-fsanitize=implicit-bitfield-conversion``: Implicit conversion from
+ integer of larger bit width to smaller bitfield, if that results in data
+ loss. This includes unsigned/signed truncations and sign changes, similarly
+ to how the ``-fsanitize=implicit-integer-conversion`` group works, but
+ explicitly for bitfields.
- ``-fsanitize=nonnull-attribute``: Passing null pointer as a function
parameter which is declared to never be null.
- ``-fsanitize=null``: Use of a null pointer or creation of a null
@@ -193,8 +198,8 @@ Available checks are:
signed division overflow (``INT_MIN/-1``). Note that checks are still
added even when ``-fwrapv`` is enabled. This sanitizer does not check for
lossy implicit conversions performed before the computation (see
- ``-fsanitize=implicit-conversion``). Both of these two issues are handled
- by ``-fsanitize=implicit-conversion`` group of checks.
+ ``-fsanitize=implicit-integer-conversion``). Both of these two issues are handled
+ by ``-fsanitize=implicit-integer-conversion`` group of checks.
- ``-fsanitize=unreachable``: If control flow reaches an unreachable
program point.
- ``-fsanitize=unsigned-integer-overflow``: Unsigned integer overflow, where
@@ -202,7 +207,7 @@ Available checks are:
type. Unlike signed integer overflow, this is not undefined behavior, but
it is often unintentional. This sanitizer does not check for lossy implicit
conversions performed before such a computation
- (see ``-fsanitize=implicit-conversion``).
+ (see ``-fsanitize=implicit-integer-conversion``).
- ``-fsanitize=vla-bound``: A variable-length array whose bound
does not evaluate to a positive value.
- ``-fsanitize=vptr``: Use of an object whose vptr indicates that it is of
@@ -224,11 +229,15 @@ You can also use the following check groups:
- ``-fsanitize=implicit-integer-arithmetic-value-change``: Catches implicit
conversions that change the arithmetic value of the integer. Enables
``implicit-signed-integer-truncation`` and ``implicit-integer-sign-change``.
- - ``-fsanitize=implicit-conversion``: Checks for suspicious
- behavior of implicit conversions. Enables
+ - ``-fsanitize=implicit-integer-conversion``: Checks for suspicious
+ behavior of implicit integer conversions. Enables
``implicit-unsigned-integer-truncation``,
``implicit-signed-integer-truncation``, and
``implicit-integer-sign-change``.
+ - ``-fsanitize=implicit-conversion``: Checks for suspicious
+ behavior of implicit conversions. Enables
+ ``implicit-integer-conversion``, and
+ ``implicit-bitfield-conversion``.
- ``-fsanitize=integer``: Checks for undefined or suspicious integer
behavior (e.g. unsigned integer overflow).
Enables ``signed-integer-overflow``, ``unsigned-integer-overflow``,
diff --git a/clang/include/clang/Basic/Sanitizers.def b/clang/include/clang/Basic/Sanitizers.def
index c2137e3f61f645..b228ffd07ee745 100644
--- a/clang/include/clang/Basic/Sanitizers.def
+++ b/clang/include/clang/Basic/Sanitizers.def
@@ -163,24 +163,24 @@ SANITIZER_GROUP("implicit-integer-arithmetic-value-change",
ImplicitIntegerArithmeticValueChange,
ImplicitIntegerSignChange | ImplicitSignedIntegerTruncation)
-SANITIZER("objc-cast", ObjCCast)
+SANITIZER_GROUP("implicit-integer-conversion", ImplicitIntegerConversion,
+ ImplicitIntegerArithmeticValueChange |
+ ImplicitUnsignedIntegerTruncation)
-// FIXME:
-//SANITIZER_GROUP("implicit-integer-conversion", ImplicitIntegerConversion,
-// ImplicitIntegerArithmeticValueChange |
-// ImplicitUnsignedIntegerTruncation)
-//SANITIZER_GROUP("implicit-conversion", ImplicitConversion,
-// ImplicitIntegerConversion)
+// Implicit bitfield sanitizers
+SANITIZER("implicit-bitfield-conversion", ImplicitBitfieldConversion)
SANITIZER_GROUP("implicit-conversion", ImplicitConversion,
- ImplicitIntegerArithmeticValueChange |
- ImplicitUnsignedIntegerTruncation)
+ ImplicitIntegerConversion |
+ ImplicitBitfieldConversion)
SANITIZER_GROUP("integer", Integer,
- ImplicitConversion | IntegerDivideByZero | Shift |
+ ImplicitIntegerConversion | IntegerDivideByZero | Shift |
SignedIntegerOverflow | UnsignedIntegerOverflow |
UnsignedShiftBase)
+SANITIZER("objc-cast", ObjCCast)
+
SANITIZER("local-bounds", LocalBounds)
SANITIZER_GROUP("bounds", Bounds, ArrayBounds | LocalBounds)
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 59a7fe8925001c..f04849f31b377c 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -5571,11 +5571,52 @@ LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
break;
}
- RValue RV = EmitAnyExpr(E->getRHS());
+ llvm::Value *Previous = nullptr;
+ RValue RV;
+ QualType SrcType = E->getRHS()->getType();
+ // Check if LHS is a bitfield, if RHS contains an implicit cast expression
+ // we want to extract that value and potentially (if the bitfield sanitizer
+ // is enabled) use it to check for an implicit conversion.
+ if (E->getLHS()->refersToBitField()) {
+ // Get the RHS before scalar conversion.
+ if (auto *ICE = GetOriginalRHSForBitfieldSanitizer(E)) {
+ SrcType = ICE->getSubExpr()->getType();
+ Previous = EmitScalarExpr(ICE->getSubExpr());
+ // Pass default ScalarConversionOpts to avoid emitting
+ // integer sanitizer checks as E refers to bitfield.
+ llvm::Value *RHS = EmitScalarConversion(
+ Previous, SrcType, ICE->getType(), ICE->getExprLoc());
+ RV = RValue::get(RHS);
+ }
+ }
+
+ // Otherwise, visit RHS as usual.
+ if (!Previous)
+ RV = EmitAnyExpr(E->getRHS());
+
LValue LV = EmitCheckedLValue(E->getLHS(), TCK_Store);
+
if (RV.isScalar())
EmitNullabilityCheck(LV, RV.getScalarVal(), E->getExprLoc());
- EmitStoreThroughLValue(RV, LV);
+
+ if (LV.isBitField() && RV.isScalar()) {
+ llvm::Value *Result;
+ // If bitfield sanitizers are enabled we want to use the result
+ // to check whether a truncation or sign change has occurred.
+ if (SanOpts.has(SanitizerKind::ImplicitBitfieldConversion))
+ EmitStoreThroughBitfieldLValue(RV, LV, &Result);
+ else
+ EmitStoreThroughBitfieldLValue(RV, LV);
+
+ // If the expression contained an implicit conversion, make sure
+ // to use the value before the scalar conversion.
+ llvm::Value *Src = Previous ? Previous : RV.getScalarVal();
+ QualType DstType = E->getLHS()->getType();
+ EmitBitfieldConversionCheck(Src, SrcType, Result, DstType,
+ LV.getBitFieldInfo(), E->getExprLoc());
+ } else
+ EmitStoreThroughLValue(RV, LV);
+
if (getLangOpts().OpenMP)
CGM.getOpenMPRuntime().checkAndEmitLastprivateConditional(*this,
E->getLHS());
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 74d94259572dc2..aed591cb1d44ed 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -15,6 +15,7 @@
#include "CGDebugInfo.h"
#include "CGObjCRuntime.h"
#include "CGOpenMPRuntime.h"
+#include "CGRecordLayout.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "ConstantEmitter.h"
@@ -308,6 +309,7 @@ class ScalarExprEmitter
llvm::Type *DstTy, SourceLocation Loc);
/// Known implicit conversion check kinds.
+ /// This is used for bitfield conversion checks as well.
/// Keep in sync with the enum of the same name in ubsan_handlers.h
enum ImplicitConversionCheckKind : unsigned char {
ICCK_IntegerTruncation = 0, // Legacy, was only used by clang 7.
@@ -1116,7 +1118,7 @@ static llvm::Value *EmitIsNegativeTestHelper(Value *V, QualType VType,
return Builder.CreateICmp(llvm::ICmpInst::ICMP_SLT, V, Zero,
llvm::Twine(Name) + "." + V->getName() +
".negativitycheck");
-};
+}
// Should be called within CodeGenFunction::SanitizerScope RAII scope.
// Returns 'i1 false' when the conversion Src -> Dst changed the sign.
@@ -1242,6 +1244,136 @@ void ScalarExprEmitter::EmitIntegerSignChangeCheck(Value *Src, QualType SrcType,
{Src, Dst});
}
+// Should be called within CodeGenFunction::SanitizerScope RAII scope.
+// Returns 'i1 false' when the truncation Src -> Dst was lossy.
+static std::pair<ScalarExprEmitter::ImplicitConversionCheckKind,
+ std::pair<llvm::Value *, SanitizerMask>>
+EmitBitfieldTruncationCheckHelper(Value *Src, QualType SrcType, Value *Dst,
+ QualType DstType, CGBuilderTy &Builder) {
+ bool SrcSigned = SrcType->isSignedIntegerOrEnumerationType();
+ bool DstSigned = DstType->isSignedIntegerOrEnumerationType();
+
+ ScalarExprEmitter::ImplicitConversionCheckKind Kind;
+ if (!SrcSigned && !DstSigned)
+ Kind = ScalarExprEmitter::ICCK_UnsignedIntegerTruncation;
+ else
+ Kind = ScalarExprEmitter::ICCK_SignedIntegerTruncation;
+
+ llvm::Value *Check = nullptr;
+ // 1. Extend the truncated value back to the same width as the Src.
+ Check = Builder.CreateIntCast(Dst, Src->getType(), DstSigned, "bf.anyext");
+ // 2. Equality-compare with the original source value
+ Check = Builder.CreateICmpEQ(Check, Src, "bf.truncheck");
+ // If the comparison result is 'i1 false', then the truncation was lossy.
+
+ return std::make_pair(
+ Kind, std::make_pair(Check, SanitizerKind::ImplicitBitfieldConversion));
+}
+
+// Should be called within CodeGenFunction::SanitizerScope RAII scope.
+// Returns 'i1 false' when the conversion Src -> Dst changed the sign.
+static std::pair<ScalarExprEmitter::ImplicitConversionCheckKind,
+ std::pair<llvm::Value *, SanitizerMask>>
+EmitBitfieldSignChangeCheckHelper(Value *Src, QualType SrcType, Value *Dst,
+ QualType DstType, CGBuilderTy &Builder) {
+ // 1. Was the old Value negative?
+ llvm::Value *SrcIsNegative =
+ EmitIsNegativeTestHelper(Src, SrcType, "bf.src", Builder);
+ // 2. Is the new Value negative?
+ llvm::Value *DstIsNegative =
+ EmitIsNegativeTestHelper(Dst, DstType, "bf.dst", Builder);
+ // 3. Now, was the 'negativity status' preserved during the conversion?
+ // NOTE: conversion from negative to zero is considered to change the sign.
+ // (We want to get 'false' when the conversion changed the sign)
+ // So we should just equality-compare the negativity statuses.
+ llvm::Value *Check = nullptr;
+ Check =
+ Builder.CreateICmpEQ(SrcIsNegative, DstIsNegative, "bf.signchangecheck");
+ // If the comparison result is 'false', then the conversion changed the sign.
+ return std::make_pair(
+ ScalarExprEmitter::ICCK_IntegerSignChange,
+ std::make_pair(Check, SanitizerKind::ImplicitBitfieldConversion));
+}
+
+void CodeGenFunction::EmitBitfieldConversionCheck(Value *Src, QualType SrcType,
+ Value *Dst, QualType DstType,
+ const CGBitFieldInfo &Info,
+ SourceLocation Loc) {
+
+ if (!SanOpts.has(SanitizerKind::ImplicitBitfieldConversion))
+ return;
+
+ // We only care about int->int conversions here.
+ // We ignore conversions to/from pointer and/or bool.
+ if (!PromotionIsPotentiallyEligibleForImplicitIntegerConversionCheck(SrcType,
+ DstType))
+ return;
+
+ if (DstType->isBooleanType() || SrcType->isBooleanType())
+ return;
+
+ // This should be truncation of integral types.
+ assert(isa<llvm::IntegerType>(Src->getType()) &&
+ isa<llvm::IntegerType>(Dst->getType()) && "non-integer llvm type");
+
+ // TODO: Calculate src width to avoid emitting code
+ // for unecessary cases.
+ unsigned SrcBits = ConvertType(SrcType)->getScalarSizeInBits();
+ unsigned DstBits = Info.Size;
+
+ bool SrcSigned = SrcType->isSignedIntegerOrEnumerationType();
+ bool DstSigned = DstType->isSignedIntegerOrEnumerationType();
+
+ CodeGenFunction::SanitizerScope SanScope(this);
+
+ std::pair<ScalarExprEmitter::ImplicitConversionCheckKind,
+ std::pair<llvm::Value *, SanitizerMask>>
+ Check;
+
+ // Truncation
+ bool EmitTruncation = DstBits < SrcBits;
+ // If Dst is signed and Src unsigned, we want to be more specific
+ // about the CheckKind we emit, in this case we want to emit
+ // ICCK_SignedIntegerTruncationOrSignChange.
+ bool EmitTruncationFromUnsignedToSigned =
+ EmitTruncation && DstSigned && !SrcSigned;
+ // Sign change
+ bool SameTypeSameSize = SrcSigned == DstSigned && SrcBits == DstBits;
+ bool BothUnsigned = !SrcSigned && !DstSigned;
+ bool LargerSigned = (DstBits > SrcBits) && DstSigned;
+ // We can avoid emitting sign change checks in some obvious cases
+ // 1. If Src and Dst have the same signedness and size
+ // 2. If both are unsigned sign check is unecessary!
+ // 3. If Dst is signed and bigger than Src, either
+ // sign-extension or zero-extension will make sure
+ // the sign remains.
+ bool EmitSignChange = !SameTypeSameSize && !BothUnsigned && !LargerSigned;
+
+ if (EmitTruncation)
+ Check =
+ EmitBitfieldTruncationCheckHelper(Src, SrcType, Dst, DstType, Builder);
+ else if (EmitSignChange) {
+ assert(((SrcBits != DstBits) || (SrcSigned != DstSigned)) &&
+ "either the widths should be different, or the signednesses.");
+ Check =
+ EmitBitfieldSignChangeCheckHelper(Src, SrcType, Dst, DstType, Builder);
+ } else
+ return;
+
+ ScalarExprEmitter::ImplicitConversionCheckKind CheckKind = Check.first;
+ if (EmitTruncationFromUnsignedToSigned)
+ CheckKind = ScalarExprEmitter::ICCK_SignedIntegerTruncationOrSignChange;
+
+ llvm::Constant *StaticArgs[] = {
+ EmitCheckSourceLocation(Loc), EmitCheckTypeDescriptor(SrcType),
+ EmitCheckTypeDescriptor(DstType),
+ llvm::ConstantInt::get(Builder.getInt8Ty(), CheckKind),
+ llvm::ConstantInt::get(Builder.getInt32Ty(), Info.Size)};
+
+ EmitCheck(Check.second, SanitizerHandler::ImplicitConversion, StaticArgs,
+ {Src, Dst});
+}
+
Value *ScalarExprEmitter::EmitScalarCast(Value *Src, QualType SrcType,
QualType DstType, llvm::Type *SrcTy,
llvm::Type *DstTy,
@@ -2614,6 +2746,8 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
llvm::PHINode *atomicPHI = nullptr;
llvm::Value *value;
llvm::Value *input;
+ llvm::Value *Previous = nullptr;
+ QualType SrcType = E->getType();
int amount = (isInc ? 1 : -1);
bool isSubtraction = !isInc;
@@ -2702,7 +2836,8 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
"base or promoted) will be signed, or the bitwidths will match.");
}
if (CGF.SanOpts.hasOneOf(
- SanitizerKind::ImplicitIntegerArithmeticValueChange) &&
+ SanitizerKind::ImplicitIntegerArithmeticValueChange |
+ SanitizerKind::ImplicitBitfieldConversion) &&
canPerformLossyDemotionCheck) {
// While `x += 1` (for `x` with width less than int) is modeled as
// promotion+arithmetics+demotion, and we can catch lossy demotion with
@@ -2713,13 +2848,26 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
// the increment/decrement in the wider type, and finally
// perform the demotion. This will catch lossy demotions.
+ // We have a special case for bitfields defined using all the bits of the
+ // type. In this case we need to do the same trick as for the integer
+ // sanitizer checks, i.e., promotion -> increment/decrement -> demotion.
+
value = EmitScalarConversion(value, type, promotedType, E->getExprLoc());
Value *amt = llvm::ConstantInt::get(value->getType(), amount, true);
value = Builder.CreateAdd(value, amt, isInc ? "inc" : "dec");
// Do pass non-default ScalarConversionOpts so that sanitizer check is
- // emitted.
+ // emitted if LV is not a bitfield, otherwise the bitfield sanitizer
+ // checks will take care of the conversion.
+ ScalarConversionOpts Opts;
+ if (!LV.isBitField())
+ Opts = ScalarConversionOpts(CGF.SanOpts);
+ else if (CGF.SanOpts.has(SanitizerKind::ImplicitBitfieldConversion)) {
+ Previous = value;
+ SrcType = promotedType;
+ }
+
value = EmitScalarConversion(value, promotedType, type, E->getExprLoc(),
- ScalarConversionOpts(CGF.SanOpts));
+ Opts);
// Note that signed integer inc/dec with width less than int can't
// overflow because of promotion rules; we're just eliding a few steps
@@ -2904,9 +3052,12 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
}
// Store the updated result through the lvalue.
- if (LV.isBitField())
+ if (LV.isBitField()) {
+ Value *Src = Previous ? Previous : value;
CGF.EmitStoreThroughBitfieldLValue(RValue::get(value), LV, &value);
- else
+ CGF.EmitBitfieldConversionCheck(Src, SrcType, value, E->getType(),
+ LV.getBitFieldInfo(), E->getExprLoc());
+ } else
CGF.EmitStoreThroughLValue(RValue::get(value), LV);
// If this is a postinc, return the value read from memory, otherwise use the
@@ -3411,8 +3562,15 @@ LValue ScalarExprEmitter::EmitCompoundAssignLValue(
// Convert the result back to the LHS type,
// potentially with Implicit Conversion sanitizer check.
- Result = EmitScalarConversion(Result, PromotionTypeCR, LHSTy, Loc,
- ScalarConversionOpts(CGF.SanOpts));
+ // If LHSLV is a bitfield, use default ScalarConversionOpts
+ // to avoid emit any implicit integer checks.
+ Value *Previous = nullptr;
+ if (LHSLV.isBitField()) {
+ Previous = Result;
+ Result = EmitScalarConversion(Result, PromotionTypeCR, LHSTy, Loc);
+ } else
+ Result = EmitScalarConversion(Result, PromotionTypeCR, LHSTy, Loc,
+ ScalarConversionOpts(CGF.SanOpts));
if (atomicPHI) {
llvm::BasicBlock *curBlock = Builder.GetInsertBlock();
@@ -3431,9 +3589,14 @@ LValue ScalarExprEmitter::EmitCompoundAssignLValue(
// specially because the result is altered by the store, i.e., [C99 6.5.16p1]
// 'An assignment expression has the value of the left operand after the
// assignment...'.
- if (LHSLV.isBitField())
+ if (LHSLV.isBitField()) {
+ Value *Src = Previous ? Previous : Result;
+ QualType SrcType = E->getRHS()->getType();
+ QualType DstType = E->getLHS()->getType();
CGF.EmitStoreThroughBitfieldLValue(RValue::get(Result), LHSLV, &Result);
- else
+ CGF.EmitBitfieldConversionCheck(Src, SrcType, Result, DstType,
+ LHSLV.getBitFieldInfo(), E->getExprLoc());
+ } else
CGF.EmitStoreThroughLValue(RValue::get(Result), LHSLV);
if (CGF.getLangOpts().OpenMP)
@@ -4545,6 +4708,19 @@ Value *ScalarExprEmitter::EmitCompare(const BinaryOperator *E,
E->getExprLoc());
}
+ImplicitCastExpr *
+CodeGenFunction::GetOriginalRHSForBitfieldSanitizer(const BinaryOperator *E) {
+ // In case we have the integer or bitfield sanitizer checks enabled
+ // we want to get the expression before scalar conversion.
+ if (auto *ICE = dyn_cast<ImplicitCastExpr>(E->getRHS())) {
+ CastKind Kind = ICE->getCastKind();
+ if (Kind == CK_IntegralCast) {
+ return ICE;
+ }
+ }
+ return nullptr;
+}
+
Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
bool Ignore = TestAndClearIgnoreResultAssign();
@@ -4573,7 +4749,27 @@ Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
case Qualifiers::OCL_None:
// __block variables need to have the rhs evaluated first, plus
// this should improve codegen just a little.
- RHS = Visit(E->getRHS());
+ Value *Previous = nullptr;
+ QualType SrcType = E->getRHS()->getType();
+ // Check if LHS is a bitfield, if RHS contains an implicit cast expression
+ // we want to extract that value and potentially (if the bitfield sanitizer
+ // is enabled) use it to check for an implicit conversion.
+ if (E->getLHS()->refersToBitField()) {
+ // Get the RHS before scalar conversion
+ if (auto *ICE = CGF.GetOriginalRHSForBitfieldSanitizer(E)) {
+ SrcType = ICE->getSubExpr()->getType();
+ Previous = Visit(ICE->getSubExpr());
+ // Pass default ScalarConversionOpts to avoid emitting
+ // integer sanitizer checks as E refers to bitfield.
+ RHS = EmitScalarConversion(Previous, SrcType, ICE->getType(),
+ ICE->getExprLoc());
+ }
+ }
+
+ // Otherwise, visit RHS as usual.
+ if (!Previous)
+ RHS = Visit(E->getRHS());
+
LHS = EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
// Store the value into the LHS. Bit-fields are handled specially
@@ -4581,7 +4777,13 @@ Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
// 'An assignment expression has the value of the left operand after
// the assignment...'.
if (LHS.isBitField()) {
+ // If the expression contained an implicit conversion, make sure
+ // to use the value before the scalar conversion.
+ Value *Src = Previous ? Previous : RHS;
+ QualType DstType = E->getLHS()->getType();
CGF.EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, &RHS);
+ CGF.EmitBitfieldConversionCheck(Src, SrcType, RHS, DstType,
+ LHS.getBitFieldInfo(), E->getExprLoc());
} else {
CGF.EmitNullabilityCheck(LHS, RHS, E->getExprLoc());
CGF.EmitStoreThroughLValue(RValue::get(RHS), LHS);
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 06327a18471778..00172a8eaefdf8 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -2697,6 +2697,18 @@ class CodeGenFunction : public CodeGenTypeCache {
/// expression and compare the result against zero, returning an Int1Ty value.
llvm::Value *EvaluateExprAsBool(const Expr *E);
+ /// Retrieve the implicit cast expression of the rhs in a binary operator
+ /// expression This is used for implicit bitfield conversion checks, which
+ /// must compare with the value before truncation.
+ ImplicitCastExpr *GetOriginalRHSForBitfieldSanitizer(const BinaryOperator *E);
+
+ /// Emit a check that an [implicit] conversion of a bitfield. It is not UB,
+ /// so we use the value after conversion.
+ void EmitBitfieldConversionCheck(llvm::Value *Src, QualType SrcType,
+ llvm::Value *Dst, QualType DstType,
+ const CGBitFieldInfo &Info,
+ SourceLocation Loc);
+
/// EmitIgnoredExpr - Emit an expression in a context which ignores the result.
void EmitIgnoredExpr(const Expr *E);
diff --git a/clang/test/CodeGen/ubsan-bitfield-conversion.c b/clang/test/CodeGen/ubsan-bitfield-conversion.c
new file mode 100644
index 00000000000000..5f9623ca8e295f
--- /dev/null
+++ b/clang/test/CodeGen/ubsan-bitfield-conversion.c
@@ -0,0 +1,61 @@
+// UN: %clang -fsanitize=implicit-bitfield-conversion -target x86_64-linux -S -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,CHECK-BITFIELD-CONVERSION
+// RUN: %clang -fsanitize=implicit-integer-conversion -target x86_64-linux -S -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK
+// UN: %clang -fsanitize=implicit-conversion -target x86_64-linux -S -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,CHECK-BITFIELD-CONVERSION
+
+typedef struct _xx {
+ int x1:3;
+ char x2:2;
+} xx, *pxx;
+
+xx vxx;
+
+// CHECK-LABEL: define{{.*}} void @foo1
+void foo1(int x) {
+ vxx.x1 = x;
+ // CHECK: store i8 %{{.*}}
+ // CHECK-NEXT: [[BFRESULTSHL:%.*]] = shl i8 {{.*}}, 5
+ // CHECK-NEXT: [[BFRESULTASHR:%.*]] = ashr i8 [[BFRESULTSHL]], 5
+ // CHECK-NEXT: [[BFRESULTCAST:%.*]] = sext i8 [[BFRESULTASHR]] to i32
+ // CHECK-BITFIELD-CONVERSION: call void @__ubsan_handle_implicit_conversion
+ // CHECK-BITFIELD-CONVERSION-NEXT: br label %[[CONT:.*]], !nosanitize !6
+ // CHECK-BITFIELD-CONVERSION: [[CONT]]:
+ // CHECK-NEXT: ret void
+}
+
+// CHECK-LABEL: define{{.*}} void @foo2
+void foo2(int x) {
+ vxx.x2 = x;
+ // CHECK: store i8 %{{.*}}
+ // CHECK-NEXT: [[BFRESULTSHL:%.*]] = shl i8 {{.*}}, 6
+ // CHECK-NEXT: [[BFRESULTASHR:%.*]] = ashr i8 [[BFRESULTSHL]], 6
+ // CHECK-BITFIELD-CONVERSION: call void @__ubsan_handle_implicit_conversion
+ // CHECK-BITFIELD-CONVERSION-NEXT: br label %[[CONT:.*]], !nosanitize !6
+ // CHECK-BITFIELD-CONVERSION: [[CONT]]:
+ // CHECK-NEXT: ret void
+}
+
+// CHECK-LABEL: define{{.*}} void @foo3
+void foo3() {
+ vxx.x1++;
+ // CHECK: store i8 %{{.*}}
+ // CHECK-NEXT: [[BFRESULTSHL:%.*]] = shl i8 {{.*}}, 5
+ // CHECK-NEXT: [[BFRESULTASHR:%.*]] = ashr i8 [[BFRESULTSHL]], 5
+ // CHECK-NEXT: [[BFRESULTCAST:%.*]] = sext i8 [[BFRESULTASHR]] to i32
+ // CHECK-BITFIELD-CONVERSION: call void @__ubsan_handle_implicit_conversion
+ // CHECK-BITFIELD-CONVERSION-NEXT: br label %[[CONT:.*]], !nosanitize !6
+ // CHECK-BITFIELD-CONVERSION: [[CONT]]:
+ // CHECK-NEXT: ret void
+}
+
+// CHECK-LABEL: define{{.*}} void @foo4
+void foo4(int x) {
+ vxx.x1 += x;
+ // CHECK: store i8 %{{.*}}
+ // CHECK-NEXT: [[BFRESULTSHL:%.*]] = shl i8 {{.*}}, 5
+ // CHECK-NEXT: [[BFRESULTASHR:%.*]] = ashr i8 [[BFRESULTSHL]], 5
+ // CHECK-NEXT: [[BFRESULTCAST:%.*]] = sext i8 [[BFRESULTASHR]] to i32
+ // CHECK-BITFIELD-CONVERSION: call void @__ubsan_handle_implicit_conversion
+ // CHECK-BITFIELD-CONVERSION-NEXT: br label %[[CONT:.*]], !nosanitize !6
+ // CHECK-BITFIELD-CONVERSION: [[CONT]]:
+ // CHECK-NEXT: ret void
+}
\ No newline at end of file
diff --git a/compiler-rt/lib/ubsan/ubsan_handlers.cpp b/compiler-rt/lib/ubsan/ubsan_handlers.cpp
index 0f16507d5d88f1..27d01653f088da 100644
--- a/compiler-rt/lib/ubsan/ubsan_handlers.cpp
+++ b/compiler-rt/lib/ubsan/ubsan_handlers.cpp
@@ -555,13 +555,11 @@ static void handleImplicitConversion(ImplicitConversionData *Data,
ReportOptions Opts, ValueHandle Src,
ValueHandle Dst) {
SourceLocation Loc = Data->Loc.acquire();
- ErrorType ET = ErrorType::GenericUB;
-
const TypeDescriptor &SrcTy = Data->FromType;
const TypeDescriptor &DstTy = Data->ToType;
-
bool SrcSigned = SrcTy.isSignedIntegerTy();
bool DstSigned = DstTy.isSignedIntegerTy();
+ ErrorType ET = ErrorType::GenericUB;
switch (Data->Kind) {
case ICCK_IntegerTruncation: { // Legacy, no longer used.
@@ -594,14 +592,23 @@ static void handleImplicitConversion(ImplicitConversionData *Data,
ScopedReport R(Opts, Loc, ET);
+ // In the case we have a bitfield, we want to explicitly say so in the
+ // error message.
// FIXME: is it possible to dump the values as hex with fixed width?
-
- Diag(Loc, DL_Error, ET,
- "implicit conversion from type %0 of value %1 (%2-bit, %3signed) to "
- "type %4 changed the value to %5 (%6-bit, %7signed)")
- << SrcTy << Value(SrcTy, Src) << SrcTy.getIntegerBitWidth()
- << (SrcSigned ? "" : "un") << DstTy << Value(DstTy, Dst)
- << DstTy.getIntegerBitWidth() << (DstSigned ? "" : "un");
+ if (Data->BitfieldBits)
+ Diag(Loc, DL_Error, ET,
+ "implicit conversion from type %0 of value %1 (%2-bit, %3signed) to "
+ "type %4 changed the value to %5 (%6-bit bitfield, %7signed)")
+ << SrcTy << Value(SrcTy, Src) << SrcTy.getIntegerBitWidth()
+ << (SrcSigned ? "" : "un") << DstTy << Value(DstTy, Dst)
+ << Data->BitfieldBits << (DstSigned ? "" : "un");
+ else
+ Diag(Loc, DL_Error, ET,
+ "implicit conversion from type %0 of value %1 (%2-bit, %3signed) to "
+ "type %4 changed the value to %5 (%6-bit, %7signed)")
+ << SrcTy << Value(SrcTy, Src) << SrcTy.getIntegerBitWidth()
+ << (SrcSigned ? "" : "un") << DstTy << Value(DstTy, Dst)
+ << DstTy.getIntegerBitWidth() << (DstSigned ? "" : "un");
}
void __ubsan::__ubsan_handle_implicit_conversion(ImplicitConversionData *Data,
diff --git a/compiler-rt/lib/ubsan/ubsan_handlers.h b/compiler-rt/lib/ubsan/ubsan_handlers.h
index 3bd5046de3d7d1..bae661a56833dd 100644
--- a/compiler-rt/lib/ubsan/ubsan_handlers.h
+++ b/compiler-rt/lib/ubsan/ubsan_handlers.h
@@ -147,6 +147,7 @@ struct ImplicitConversionData {
const TypeDescriptor &FromType;
const TypeDescriptor &ToType;
/* ImplicitConversionCheckKind */ unsigned char Kind;
+ unsigned int BitfieldBits;
};
/// \brief Implict conversion that changed the value.
>From bcf44e0593ba6215bec216f1bc9018d6b3583a70 Mon Sep 17 00:00:00 2001
From: Zonotora <Zonotora at hotmail.com>
Date: Thu, 15 Feb 2024 11:44:22 +0100
Subject: [PATCH 3/3] [clang][UBSan] Update testcases
Update testcases due to new -fsanitize options regarding bitfields
---
clang/test/Driver/fsanitize.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/clang/test/Driver/fsanitize.c b/clang/test/Driver/fsanitize.c
index 1671825042c323..571f79a6e7f70d 100644
--- a/clang/test/Driver/fsanitize.c
+++ b/clang/test/Driver/fsanitize.c
@@ -35,20 +35,20 @@
// RUN: %clang --target=%itanium_abi_triple -fsanitize=integer %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-INTEGER -implicit-check-not="-fsanitize-address-use-after-scope"
// CHECK-INTEGER: "-fsanitize={{((signed-integer-overflow|unsigned-integer-overflow|integer-divide-by-zero|shift-base|shift-exponent|implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change|unsigned-shift-base),?){9}"}}
-// RUN: %clang -fsanitize=implicit-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-conversion,CHECK-implicit-conversion-RECOVER
-// RUN: %clang -fsanitize=implicit-conversion -fsanitize-recover=implicit-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-conversion,CHECK-implicit-conversion-RECOVER
-// RUN: %clang -fsanitize=implicit-conversion -fno-sanitize-recover=implicit-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-conversion,CHECK-implicit-conversion-NORECOVER
-// RUN: %clang -fsanitize=implicit-conversion -fsanitize-trap=implicit-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-conversion,CHECK-implicit-conversion-TRAP
-// CHECK-implicit-conversion: "-fsanitize={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-RECOVER: "-fsanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-RECOVER-NOT: "-fno-sanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-RECOVER-NOT: "-fsanitize-trap={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-NORECOVER-NOT: "-fno-sanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}} // ???
-// CHECK-implicit-conversion-NORECOVER-NOT: "-fsanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-NORECOVER-NOT: "-fsanitize-trap={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-TRAP: "-fsanitize-trap={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-TRAP-NOT: "-fsanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
-// CHECK-implicit-conversion-TRAP-NOT: "-fno-sanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// RUN: %clang -fsanitize=implicit-integer-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-integer-conversion,CHECK-implicit-integer-conversion-RECOVER
+// RUN: %clang -fsanitize=implicit-integer-conversion -fsanitize-recover=implicit-integer-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-integer-conversion,CHECK-implicit-integer-conversion-RECOVER
+// RUN: %clang -fsanitize=implicit-integer-conversion -fno-sanitize-recover=implicit-integer-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-integer-conversion,CHECK-implicit-integer-conversion-NORECOVER
+// RUN: %clang -fsanitize=implicit-integer-conversion -fsanitize-trap=implicit-integer-conversion %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-integer-conversion,CHECK-implicit-integer-conversion-TRAP
+// CHECK-implicit-integer-conversion: "-fsanitize={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-RECOVER: "-fsanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-RECOVER-NOT: "-fno-sanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-RECOVER-NOT: "-fsanitize-trap={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-NORECOVER-NOT: "-fno-sanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}} // ???
+// CHECK-implicit-integer-conversion-NORECOVER-NOT: "-fsanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-NORECOVER-NOT: "-fsanitize-trap={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-TRAP: "-fsanitize-trap={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-TRAP-NOT: "-fsanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
+// CHECK-implicit-integer-conversion-TRAP-NOT: "-fno-sanitize-recover={{((implicit-unsigned-integer-truncation|implicit-signed-integer-truncation|implicit-integer-sign-change),?){3}"}}
// RUN: %clang -fsanitize=implicit-integer-arithmetic-value-change %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-integer-arithmetic-value-change,CHECK-implicit-integer-arithmetic-value-change-RECOVER
// RUN: %clang -fsanitize=implicit-integer-arithmetic-value-change -fsanitize-recover=implicit-integer-arithmetic-value-change %s -### 2>&1 | FileCheck %s --check-prefixes=CHECK-implicit-integer-arithmetic-value-change,CHECK-implicit-integer-arithmetic-value-change-RECOVER
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