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//==- ExprInspectionChecker.cpp - Used for regression tests ------*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Taint.h"
#include "clang/Analysis/IssueHash.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Checkers/SValExplainer.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicExtent.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/ScopedPrinter.h"
using namespace clang;
using namespace ento;
namespace {
class ExprInspectionChecker
: public Checker<eval::Call, check::DeadSymbols, check::EndAnalysis> {
mutable std::unique_ptr<BugType> BT;
// These stats are per-analysis, not per-branch, hence they shouldn't
// stay inside the program state.
struct ReachedStat {
ExplodedNode *ExampleNode;
unsigned NumTimesReached;
};
mutable llvm::DenseMap<const CallExpr *, ReachedStat> ReachedStats;
void analyzerEval(const CallExpr *CE, CheckerContext &C) const;
void analyzerCheckInlined(const CallExpr *CE, CheckerContext &C) const;
void analyzerWarnIfReached(const CallExpr *CE, CheckerContext &C) const;
void analyzerNumTimesReached(const CallExpr *CE, CheckerContext &C) const;
void analyzerCrash(const CallExpr *CE, CheckerContext &C) const;
void analyzerWarnOnDeadSymbol(const CallExpr *CE, CheckerContext &C) const;
void analyzerDump(const CallExpr *CE, CheckerContext &C) const;
void analyzerExplain(const CallExpr *CE, CheckerContext &C) const;
void analyzerPrintState(const CallExpr *CE, CheckerContext &C) const;
void analyzerGetExtent(const CallExpr *CE, CheckerContext &C) const;
void analyzerDumpExtent(const CallExpr *CE, CheckerContext &C) const;
void analyzerDumpElementCount(const CallExpr *CE, CheckerContext &C) const;
void analyzerHashDump(const CallExpr *CE, CheckerContext &C) const;
void analyzerDenote(const CallExpr *CE, CheckerContext &C) const;
void analyzerExpress(const CallExpr *CE, CheckerContext &C) const;
void analyzerIsTainted(const CallExpr *CE, CheckerContext &C) const;
typedef void (ExprInspectionChecker::*FnCheck)(const CallExpr *,
CheckerContext &C) const;
// Optional parameter `ExprVal` for expression value to be marked interesting.
ExplodedNode *reportBug(llvm::StringRef Msg, CheckerContext &C,
Optional<SVal> ExprVal = None) const;
ExplodedNode *reportBug(llvm::StringRef Msg, BugReporter &BR, ExplodedNode *N,
Optional<SVal> ExprVal = None) const;
const Expr *getArgExpr(const CallExpr *CE, CheckerContext &C) const;
const MemRegion *getArgRegion(const CallExpr *CE, CheckerContext &C) const;
public:
bool evalCall(const CallEvent &Call, CheckerContext &C) const;
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
void checkEndAnalysis(ExplodedGraph &G, BugReporter &BR,
ExprEngine &Eng) const;
};
} // namespace
REGISTER_SET_WITH_PROGRAMSTATE(MarkedSymbols, SymbolRef)
REGISTER_MAP_WITH_PROGRAMSTATE(DenotedSymbols, SymbolRef, const StringLiteral *)
bool ExprInspectionChecker::evalCall(const CallEvent &Call,
CheckerContext &C) const {
const auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
if (!CE)
return false;
// These checks should have no effect on the surrounding environment
// (globals should not be invalidated, etc), hence the use of evalCall.
FnCheck Handler =
llvm::StringSwitch<FnCheck>(C.getCalleeName(CE))
.Case("clang_analyzer_eval", &ExprInspectionChecker::analyzerEval)
.Case("clang_analyzer_checkInlined",
&ExprInspectionChecker::analyzerCheckInlined)
.Case("clang_analyzer_crash", &ExprInspectionChecker::analyzerCrash)
.Case("clang_analyzer_warnIfReached",
&ExprInspectionChecker::analyzerWarnIfReached)
.Case("clang_analyzer_warnOnDeadSymbol",
&ExprInspectionChecker::analyzerWarnOnDeadSymbol)
.StartsWith("clang_analyzer_explain",
&ExprInspectionChecker::analyzerExplain)
.Case("clang_analyzer_dumpExtent",
&ExprInspectionChecker::analyzerDumpExtent)
.Case("clang_analyzer_dumpElementCount",
&ExprInspectionChecker::analyzerDumpElementCount)
.StartsWith("clang_analyzer_dump",
&ExprInspectionChecker::analyzerDump)
.Case("clang_analyzer_getExtent",
&ExprInspectionChecker::analyzerGetExtent)
.Case("clang_analyzer_printState",
&ExprInspectionChecker::analyzerPrintState)
.Case("clang_analyzer_numTimesReached",
&ExprInspectionChecker::analyzerNumTimesReached)
.Case("clang_analyzer_hashDump",
&ExprInspectionChecker::analyzerHashDump)
.Case("clang_analyzer_denote", &ExprInspectionChecker::analyzerDenote)
.Case("clang_analyzer_express",
&ExprInspectionChecker::analyzerExpress)
.StartsWith("clang_analyzer_isTainted",
&ExprInspectionChecker::analyzerIsTainted)
.Default(nullptr);
if (!Handler)
return false;
(this->*Handler)(CE, C);
return true;
}
static const char *getArgumentValueString(const CallExpr *CE,
CheckerContext &C) {
if (CE->getNumArgs() == 0)
return "Missing assertion argument";
ExplodedNode *N = C.getPredecessor();
const LocationContext *LC = N->getLocationContext();
ProgramStateRef State = N->getState();
const Expr *Assertion = CE->getArg(0);
SVal AssertionVal = State->getSVal(Assertion, LC);
if (AssertionVal.isUndef())
return "UNDEFINED";
ProgramStateRef StTrue, StFalse;
std::tie(StTrue, StFalse) =
State->assume(AssertionVal.castAs<DefinedOrUnknownSVal>());
if (StTrue) {
if (StFalse)
return "UNKNOWN";
else
return "TRUE";
} else {
if (StFalse)
return "FALSE";
else
llvm_unreachable("Invalid constraint; neither true or false.");
}
}
ExplodedNode *ExprInspectionChecker::reportBug(llvm::StringRef Msg,
CheckerContext &C,
Optional<SVal> ExprVal) const {
ExplodedNode *N = C.generateNonFatalErrorNode();
reportBug(Msg, C.getBugReporter(), N, ExprVal);
return N;
}
ExplodedNode *ExprInspectionChecker::reportBug(llvm::StringRef Msg,
BugReporter &BR, ExplodedNode *N,
Optional<SVal> ExprVal) const {
if (!N)
return nullptr;
if (!BT)
BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));
auto R = std::make_unique<PathSensitiveBugReport>(*BT, Msg, N);
if (ExprVal) {
R->markInteresting(*ExprVal);
}
BR.emitReport(std::move(R));
return N;
}
const Expr *ExprInspectionChecker::getArgExpr(const CallExpr *CE,
CheckerContext &C) const {
if (CE->getNumArgs() == 0) {
reportBug("Missing argument", C);
return nullptr;
}
return CE->getArg(0);
}
const MemRegion *ExprInspectionChecker::getArgRegion(const CallExpr *CE,
CheckerContext &C) const {
const Expr *Arg = getArgExpr(CE, C);
if (!Arg)
return nullptr;
const MemRegion *MR = C.getSVal(Arg).getAsRegion();
if (!MR) {
reportBug("Cannot obtain the region", C);
return nullptr;
}
return MR;
}
void ExprInspectionChecker::analyzerEval(const CallExpr *CE,
CheckerContext &C) const {
const LocationContext *LC = C.getPredecessor()->getLocationContext();
// A specific instantiation of an inlined function may have more constrained
// values than can generally be assumed. Skip the check.
if (LC->getStackFrame()->getParent() != nullptr)
return;
reportBug(getArgumentValueString(CE, C), C);
}
void ExprInspectionChecker::analyzerWarnIfReached(const CallExpr *CE,
CheckerContext &C) const {
reportBug("REACHABLE", C);
}
void ExprInspectionChecker::analyzerNumTimesReached(const CallExpr *CE,
CheckerContext &C) const {
++ReachedStats[CE].NumTimesReached;
if (!ReachedStats[CE].ExampleNode) {
// Later, in checkEndAnalysis, we'd throw a report against it.
ReachedStats[CE].ExampleNode = C.generateNonFatalErrorNode();
}
}
void ExprInspectionChecker::analyzerCheckInlined(const CallExpr *CE,
CheckerContext &C) const {
const LocationContext *LC = C.getPredecessor()->getLocationContext();
// An inlined function could conceivably also be analyzed as a top-level
// function. We ignore this case and only emit a message (TRUE or FALSE)
// when we are analyzing it as an inlined function. This means that
// clang_analyzer_checkInlined(true) should always print TRUE, but
// clang_analyzer_checkInlined(false) should never actually print anything.
if (LC->getStackFrame()->getParent() == nullptr)
return;
reportBug(getArgumentValueString(CE, C), C);
}
void ExprInspectionChecker::analyzerExplain(const CallExpr *CE,
CheckerContext &C) const {
const Expr *Arg = getArgExpr(CE, C);
if (!Arg)
return;
SVal V = C.getSVal(Arg);
SValExplainer Ex(C.getASTContext());
reportBug(Ex.Visit(V), C);
}
void ExprInspectionChecker::analyzerDump(const CallExpr *CE,
CheckerContext &C) const {
const Expr *Arg = getArgExpr(CE, C);
if (!Arg)
return;
SVal V = C.getSVal(Arg);
llvm::SmallString<32> Str;
llvm::raw_svector_ostream OS(Str);
V.dumpToStream(OS);
reportBug(OS.str(), C);
}
void ExprInspectionChecker::analyzerGetExtent(const CallExpr *CE,
CheckerContext &C) const {
const MemRegion *MR = getArgRegion(CE, C);
if (!MR)
return;
ProgramStateRef State = C.getState();
DefinedOrUnknownSVal Size = getDynamicExtent(State, MR, C.getSValBuilder());
State = State->BindExpr(CE, C.getLocationContext(), Size);
C.addTransition(State);
}
void ExprInspectionChecker::analyzerDumpExtent(const CallExpr *CE,
CheckerContext &C) const {
const MemRegion *MR = getArgRegion(CE, C);
if (!MR)
return;
DefinedOrUnknownSVal Size =
getDynamicExtent(C.getState(), MR, C.getSValBuilder());
SmallString<64> Msg;
llvm::raw_svector_ostream Out(Msg);
Out << Size;
reportBug(Out.str(), C);
}
void ExprInspectionChecker::analyzerDumpElementCount(const CallExpr *CE,
CheckerContext &C) const {
const MemRegion *MR = getArgRegion(CE, C);
if (!MR)
return;
QualType ElementTy;
if (const auto *TVR = MR->getAs<TypedValueRegion>()) {
ElementTy = TVR->getValueType();
} else {
ElementTy =
MR->castAs<SymbolicRegion>()->getSymbol()->getType()->getPointeeType();
}
assert(!ElementTy->isPointerType());
DefinedOrUnknownSVal ElementCount =
getDynamicElementCount(C.getState(), MR, C.getSValBuilder(), ElementTy);
SmallString<128> Msg;
llvm::raw_svector_ostream Out(Msg);
Out << ElementCount;
reportBug(Out.str(), C);
}
void ExprInspectionChecker::analyzerPrintState(const CallExpr *CE,
CheckerContext &C) const {
C.getState()->dump();
}
void ExprInspectionChecker::analyzerWarnOnDeadSymbol(const CallExpr *CE,
CheckerContext &C) const {
const Expr *Arg = getArgExpr(CE, C);
if (!Arg)
return;
SVal Val = C.getSVal(Arg);
SymbolRef Sym = Val.getAsSymbol();
if (!Sym)
return;
ProgramStateRef State = C.getState();
State = State->add<MarkedSymbols>(Sym);
C.addTransition(State);
}
void ExprInspectionChecker::checkDeadSymbols(SymbolReaper &SymReaper,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
const MarkedSymbolsTy &Syms = State->get<MarkedSymbols>();
ExplodedNode *N = C.getPredecessor();
for (auto I = Syms.begin(), E = Syms.end(); I != E; ++I) {
SymbolRef Sym = *I;
if (!SymReaper.isDead(Sym))
continue;
// The non-fatal error node should be the same for all reports.
if (ExplodedNode *BugNode = reportBug("SYMBOL DEAD", C))
N = BugNode;
State = State->remove<MarkedSymbols>(Sym);
}
for (auto I : State->get<DenotedSymbols>()) {
SymbolRef Sym = I.first;
if (!SymReaper.isLive(Sym))
State = State->remove<DenotedSymbols>(Sym);
}
C.addTransition(State, N);
}
void ExprInspectionChecker::checkEndAnalysis(ExplodedGraph &G, BugReporter &BR,
ExprEngine &Eng) const {
for (auto Item : ReachedStats) {
unsigned NumTimesReached = Item.second.NumTimesReached;
ExplodedNode *N = Item.second.ExampleNode;
reportBug(llvm::to_string(NumTimesReached), BR, N);
}
ReachedStats.clear();
}
void ExprInspectionChecker::analyzerCrash(const CallExpr *CE,
CheckerContext &C) const {
LLVM_BUILTIN_TRAP;
}
void ExprInspectionChecker::analyzerHashDump(const CallExpr *CE,
CheckerContext &C) const {
const LangOptions &Opts = C.getLangOpts();
const SourceManager &SM = C.getSourceManager();
FullSourceLoc FL(CE->getArg(0)->getBeginLoc(), SM);
std::string HashContent =
getIssueString(FL, getCheckerName().getName(), "Category",
C.getLocationContext()->getDecl(), Opts);
reportBug(HashContent, C);
}
void ExprInspectionChecker::analyzerDenote(const CallExpr *CE,
CheckerContext &C) const {
if (CE->getNumArgs() < 2) {
reportBug("clang_analyzer_denote() requires a symbol and a string literal",
C);
return;
}
SymbolRef Sym = C.getSVal(CE->getArg(0)).getAsSymbol();
if (!Sym) {
reportBug("Not a symbol", C);
return;
}
const auto *E = dyn_cast<StringLiteral>(CE->getArg(1)->IgnoreParenCasts());
if (!E) {
reportBug("Not a string literal", C);
return;
}
ProgramStateRef State = C.getState();
C.addTransition(C.getState()->set<DenotedSymbols>(Sym, E));
}
namespace {
class SymbolExpressor
: public SymExprVisitor<SymbolExpressor, Optional<std::string>> {
ProgramStateRef State;
public:
SymbolExpressor(ProgramStateRef State) : State(State) {}
Optional<std::string> lookup(const SymExpr *S) {
if (const StringLiteral *const *SLPtr = State->get<DenotedSymbols>(S)) {
const StringLiteral *SL = *SLPtr;
return std::string(SL->getBytes());
}
return None;
}
Optional<std::string> VisitSymExpr(const SymExpr *S) { return lookup(S); }
Optional<std::string> VisitSymIntExpr(const SymIntExpr *S) {
if (Optional<std::string> Str = lookup(S))
return Str;
if (Optional<std::string> Str = Visit(S->getLHS()))
return (*Str + " " + BinaryOperator::getOpcodeStr(S->getOpcode()) + " " +
std::to_string(S->getRHS().getLimitedValue()) +
(S->getRHS().isUnsigned() ? "U" : ""))
.str();
return None;
}
Optional<std::string> VisitSymSymExpr(const SymSymExpr *S) {
if (Optional<std::string> Str = lookup(S))
return Str;
if (Optional<std::string> Str1 = Visit(S->getLHS()))
if (Optional<std::string> Str2 = Visit(S->getRHS()))
return (*Str1 + " " + BinaryOperator::getOpcodeStr(S->getOpcode()) +
" " + *Str2)
.str();
return None;
}
Optional<std::string> VisitSymbolCast(const SymbolCast *S) {
if (Optional<std::string> Str = lookup(S))
return Str;
if (Optional<std::string> Str = Visit(S->getOperand()))
return (Twine("(") + S->getType().getAsString() + ")" + *Str).str();
return None;
}
};
} // namespace
void ExprInspectionChecker::analyzerExpress(const CallExpr *CE,
CheckerContext &C) const {
const Expr *Arg = getArgExpr(CE, C);
if (!Arg)
return;
SVal ArgVal = C.getSVal(CE->getArg(0));
SymbolRef Sym = ArgVal.getAsSymbol();
if (!Sym) {
reportBug("Not a symbol", C);
return;
}
SymbolExpressor V(C.getState());
auto Str = V.Visit(Sym);
if (!Str) {
reportBug("Unable to express", C);
return;
}
reportBug(*Str, C, ArgVal);
}
void ExprInspectionChecker::analyzerIsTainted(const CallExpr *CE,
CheckerContext &C) const {
if (CE->getNumArgs() != 1) {
reportBug("clang_analyzer_isTainted() requires exactly one argument", C);
return;
}
const bool IsTainted =
taint::isTainted(C.getState(), CE->getArg(0), C.getLocationContext());
reportBug(IsTainted ? "YES" : "NO", C);
}
void ento::registerExprInspectionChecker(CheckerManager &Mgr) {
Mgr.registerChecker<ExprInspectionChecker>();
}
bool ento::shouldRegisterExprInspectionChecker(const CheckerManager &mgr) {
return true;
}