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ubsan: Check for null pointers given to certain builtins, such 

as memcpy, memset, memmove, and bzero.

Reviewed by: Richard Smith

Differential Revision: http://reviews.llvm.org/D9673

llvm-svn: 238657
This commit is contained in:
Nuno Lopes 2015-05-30 16:11:40 +00:00
parent b08cf1cfd2
commit 1ba2d78b9a
4 changed files with 58 additions and 12 deletions
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12
clang/lib/CodeGen/CGBuiltin.cpp
View File

@ -698,6 +698,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
std::pair<llvm::Value*, unsigned> Dest =
EmitPointerWithAlignment(E->getArg(0));
Value *SizeVal = EmitScalarExpr(E->getArg(1));
EmitNonNullArgCheck(RValue::get(Dest.first), E->getArg(0)->getType(),
E->getArg(0)->getExprLoc(), FD, 0);
Builder.CreateMemSet(Dest.first, Builder.getInt8(0), SizeVal,
Dest.second, false);
return RValue::get(Dest.first);
@ -710,6 +712,10 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
EmitPointerWithAlignment(E->getArg(1));
Value *SizeVal = EmitScalarExpr(E->getArg(2));
unsigned Align = std::min(Dest.second, Src.second);
EmitNonNullArgCheck(RValue::get(Dest.first), E->getArg(0)->getType(),
E->getArg(0)->getExprLoc(), FD, 0);
EmitNonNullArgCheck(RValue::get(Src.first), E->getArg(1)->getType(),
E->getArg(1)->getExprLoc(), FD, 1);
Builder.CreateMemCpy(Dest.first, Src.first, SizeVal, Align, false);
return RValue::get(Dest.first);
}
@ -767,6 +773,10 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
EmitPointerWithAlignment(E->getArg(1));
Value *SizeVal = EmitScalarExpr(E->getArg(2));
unsigned Align = std::min(Dest.second, Src.second);
EmitNonNullArgCheck(RValue::get(Dest.first), E->getArg(0)->getType(),
E->getArg(0)->getExprLoc(), FD, 0);
EmitNonNullArgCheck(RValue::get(Src.first), E->getArg(1)->getType(),
E->getArg(1)->getExprLoc(), FD, 1);
Builder.CreateMemMove(Dest.first, Src.first, SizeVal, Align, false);
return RValue::get(Dest.first);
}
@ -777,6 +787,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
Value *ByteVal = Builder.CreateTrunc(EmitScalarExpr(E->getArg(1)),
Builder.getInt8Ty());
Value *SizeVal = EmitScalarExpr(E->getArg(2));
EmitNonNullArgCheck(RValue::get(Dest.first), E->getArg(0)->getType(),
E->getArg(0)->getExprLoc(), FD, 0);
Builder.CreateMemSet(Dest.first, ByteVal, SizeVal, Dest.second, false);
return RValue::get(Dest.first);
}

25
clang/lib/CodeGen/CGCall.cpp
View File

@ -2719,27 +2719,28 @@ void CallArgList::freeArgumentMemory(CodeGenFunction &CGF) const {
}
}
static void emitNonNullArgCheck(CodeGenFunction &CGF, RValue RV,
QualType ArgType, SourceLocation ArgLoc,
const FunctionDecl *FD, unsigned ParmNum) {
if (!CGF.SanOpts.has(SanitizerKind::NonnullAttribute) || !FD)
void CodeGenFunction::EmitNonNullArgCheck(RValue RV, QualType ArgType,
SourceLocation ArgLoc,
const FunctionDecl *FD,
unsigned ParmNum) {
if (!SanOpts.has(SanitizerKind::NonnullAttribute) || !FD)
return;
auto PVD = ParmNum < FD->getNumParams() ? FD->getParamDecl(ParmNum) : nullptr;
unsigned ArgNo = PVD ? PVD->getFunctionScopeIndex() : ParmNum;
auto NNAttr = getNonNullAttr(FD, PVD, ArgType, ArgNo);
if (!NNAttr)
return;
CodeGenFunction::SanitizerScope SanScope(&CGF);
SanitizerScope SanScope(this);
assert(RV.isScalar());
llvm::Value *V = RV.getScalarVal();
llvm::Value *Cond =
CGF.Builder.CreateICmpNE(V, llvm::Constant::getNullValue(V->getType()));
Builder.CreateICmpNE(V, llvm::Constant::getNullValue(V->getType()));
llvm::Constant *StaticData[] = {
CGF.EmitCheckSourceLocation(ArgLoc),
CGF.EmitCheckSourceLocation(NNAttr->getLocation()),
llvm::ConstantInt::get(CGF.Int32Ty, ArgNo + 1),
EmitCheckSourceLocation(ArgLoc),
EmitCheckSourceLocation(NNAttr->getLocation()),
llvm::ConstantInt::get(Int32Ty, ArgNo + 1),
};
CGF.EmitCheck(std::make_pair(Cond, SanitizerKind::NonnullAttribute),
EmitCheck(std::make_pair(Cond, SanitizerKind::NonnullAttribute),
"nonnull_arg", StaticData, None);
}
@ -2767,7 +2768,7 @@ void CodeGenFunction::EmitCallArgs(CallArgList &Args,
for (int I = ArgTypes.size() - 1; I >= 0; --I) {
CallExpr::const_arg_iterator Arg = ArgBeg + I;
EmitCallArg(Args, *Arg, ArgTypes[I]);
emitNonNullArgCheck(*this, Args.back().RV, ArgTypes[I], Arg->getExprLoc(),
EmitNonNullArgCheck(Args.back().RV, ArgTypes[I], Arg->getExprLoc(),
CalleeDecl, ParamsToSkip + I);
}
@ -2781,7 +2782,7 @@ void CodeGenFunction::EmitCallArgs(CallArgList &Args,
CallExpr::const_arg_iterator Arg = ArgBeg + I;
assert(Arg != ArgEnd);
EmitCallArg(Args, *Arg, ArgTypes[I]);
emitNonNullArgCheck(*this, Args.back().RV, ArgTypes[I], Arg->getExprLoc(),
EmitNonNullArgCheck(Args.back().RV, ArgTypes[I], Arg->getExprLoc(),
CalleeDecl, ParamsToSkip + I);
}
}

5
clang/lib/CodeGen/CodeGenFunction.h
View File

@ -2836,6 +2836,11 @@ public:
/// conditional branch to it, for the -ftrapv checks.
void EmitTrapCheck(llvm::Value *Checked);
/// \brief Create a check for a function parameter that may potentially be
/// declared as non-null.
void EmitNonNullArgCheck(RValue RV, QualType ArgType, SourceLocation ArgLoc,
const FunctionDecl *FD, unsigned ParmNum);
/// EmitCallArg - Emit a single call argument.
void EmitCallArg(CallArgList &args, const Expr *E, QualType ArgType);

28
clang/test/CodeGen/catch-undef-behavior.c
View File

@ -371,6 +371,34 @@ void call_decl_nonnull(int *a) {
decl_nonnull(a);
}
extern void *memcpy (void *, const void *, unsigned) __attribute__((nonnull(1, 2)));
// CHECK-COMMON-LABEL: @call_memcpy_nonnull
void call_memcpy_nonnull(void *p, void *q, int sz) {
// CHECK-COMMON: icmp ne i8* {{.*}}, null
// CHECK-UBSAN: call void @__ubsan_handle_nonnull_arg
// CHECK-TRAP: call void @llvm.trap()
// CHECK-COMMON: icmp ne i8* {{.*}}, null
// CHECK-UBSAN: call void @__ubsan_handle_nonnull_arg
// CHECK-TRAP: call void @llvm.trap()
memcpy(p, q, sz);
}
extern void *memmove (void *, const void *, unsigned) __attribute__((nonnull(1, 2)));
// CHECK-COMMON-LABEL: @call_memmove_nonnull
void call_memmove_nonnull(void *p, void *q, int sz) {
// CHECK-COMMON: icmp ne i8* {{.*}}, null
// CHECK-UBSAN: call void @__ubsan_handle_nonnull_arg
// CHECK-TRAP: call void @llvm.trap()
// CHECK-COMMON: icmp ne i8* {{.*}}, null
// CHECK-UBSAN: call void @__ubsan_handle_nonnull_arg
// CHECK-TRAP: call void @llvm.trap()
memmove(p, q, sz);
}
// CHECK-COMMON-LABEL: @call_nonnull_variadic
__attribute__((nonnull)) void nonnull_variadic(int a, ...);
void call_nonnull_variadic(int a, int *b) {