24 #include "llvm/ADT/SmallString.h" 25 #include "llvm/Support/raw_ostream.h" 26 using namespace clang;
30 class StackAddrEscapeChecker
31 :
public Checker<check::PreCall, check::PreStmt<ReturnStmt>,
34 mutable std::unique_ptr<BuiltinBug> BT_stackleak;
35 mutable std::unique_ptr<BuiltinBug> BT_returnstack;
36 mutable std::unique_ptr<BuiltinBug> BT_capturedstackasync;
37 mutable std::unique_ptr<BuiltinBug> BT_capturedstackret;
41 CK_StackAddrEscapeChecker,
42 CK_StackAddrAsyncEscapeChecker,
46 DefaultBool ChecksEnabled[CK_NumCheckKinds];
48 void checkPreCall(
const CallEvent &Call, CheckerContext &C)
const;
49 void checkPreStmt(
const ReturnStmt *RS, CheckerContext &C)
const;
50 void checkEndFunction(
const ReturnStmt *RS, CheckerContext &Ctx)
const;
53 void checkReturnedBlockCaptures(
const BlockDataRegion &B,
54 CheckerContext &C)
const;
55 void checkAsyncExecutedBlockCaptures(
const BlockDataRegion &B,
56 CheckerContext &C)
const;
57 void EmitStackError(CheckerContext &C,
const MemRegion *R,
58 const Expr *RetE)
const;
59 bool isSemaphoreCaptured(
const BlockDecl &B)
const;
60 static SourceRange genName(raw_ostream &os,
const MemRegion *R,
63 getCapturedStackRegions(
const BlockDataRegion &B, CheckerContext &C);
64 static bool isArcManagedBlock(
const MemRegion *R, CheckerContext &C);
65 static bool isNotInCurrentFrame(
const MemRegion *R, CheckerContext &C);
69 SourceRange StackAddrEscapeChecker::genName(raw_ostream &os,
const MemRegion *R,
72 R = R->getBaseRegion();
78 if (
const auto *CR = dyn_cast<CompoundLiteralRegion>(R)) {
80 os <<
"stack memory associated with a compound literal " 84 }
else if (
const auto *AR = dyn_cast<AllocaRegion>(R)) {
85 const Expr *ARE = AR->getExpr();
88 os <<
"stack memory allocated by call to alloca() on line " 90 }
else if (
const auto *BR = dyn_cast<BlockDataRegion>(R)) {
91 const BlockDecl *BD = BR->getCodeRegion()->getDecl();
94 os <<
"stack-allocated block declared on line " 96 }
else if (
const auto *VR = dyn_cast<VarRegion>(R)) {
97 os <<
"stack memory associated with local variable '" << VR->getString()
99 range = VR->getDecl()->getSourceRange();
100 }
else if (
const auto *TOR = dyn_cast<CXXTempObjectRegion>(R)) {
101 QualType Ty = TOR->getValueType().getLocalUnqualifiedType();
102 os <<
"stack memory associated with temporary object of type '";
105 range = TOR->getExpr()->getSourceRange();
107 llvm_unreachable(
"Invalid region in ReturnStackAddressChecker.");
113 bool StackAddrEscapeChecker::isArcManagedBlock(
const MemRegion *R,
115 assert(R &&
"MemRegion should not be null");
116 return C.getASTContext().getLangOpts().ObjCAutoRefCount &&
117 isa<BlockDataRegion>(R);
120 bool StackAddrEscapeChecker::isNotInCurrentFrame(
const MemRegion *R,
122 const StackSpaceRegion *S = cast<StackSpaceRegion>(R->getMemorySpace());
123 return S->getStackFrame() != C.getStackFrame();
126 bool StackAddrEscapeChecker::isSemaphoreCaptured(
const BlockDecl &B)
const {
127 if (!dispatch_semaphore_tII)
129 for (
const auto &C : B.
captures()) {
130 const auto *T = C.getVariable()->getType()->getAs<
TypedefType>();
131 if (T && T->getDecl()->getIdentifier() == dispatch_semaphore_tII)
138 StackAddrEscapeChecker::getCapturedStackRegions(
const BlockDataRegion &B,
141 BlockDataRegion::referenced_vars_iterator I = B.referenced_vars_begin();
142 BlockDataRegion::referenced_vars_iterator E = B.referenced_vars_end();
143 for (; I != E; ++I) {
144 SVal Val = C.getState()->getSVal(I.getCapturedRegion());
145 const MemRegion *Region = Val.getAsRegion();
146 if (Region && isa<StackSpaceRegion>(Region->getMemorySpace()))
147 Regions.push_back(Region);
152 void StackAddrEscapeChecker::EmitStackError(CheckerContext &C,
154 const Expr *RetE)
const {
155 ExplodedNode *N = C.generateNonFatalErrorNode();
159 BT_returnstack = llvm::make_unique<BuiltinBug>(
160 this,
"Return of address to stack-allocated memory");
163 llvm::raw_svector_ostream os(buf);
164 SourceRange range = genName(os, R, C.getASTContext());
165 os <<
" returned to caller";
166 auto report = llvm::make_unique<BugReport>(*BT_returnstack, os.str(), N);
169 report->addRange(range);
170 C.emitReport(std::move(report));
173 void StackAddrEscapeChecker::checkAsyncExecutedBlockCaptures(
174 const BlockDataRegion &B, CheckerContext &C)
const {
182 if (isSemaphoreCaptured(*B.getDecl()))
184 for (
const MemRegion *Region : getCapturedStackRegions(B, C)) {
191 if (isa<BlockDataRegion>(Region))
193 ExplodedNode *N = C.generateNonFatalErrorNode();
196 if (!BT_capturedstackasync)
197 BT_capturedstackasync = llvm::make_unique<BuiltinBug>(
198 this,
"Address of stack-allocated memory is captured");
200 llvm::raw_svector_ostream Out(Buf);
201 SourceRange Range = genName(Out, Region, C.getASTContext());
202 Out <<
" is captured by an asynchronously-executed block";
204 llvm::make_unique<BugReport>(*BT_capturedstackasync, Out.str(), N);
206 Report->addRange(Range);
207 C.emitReport(std::move(Report));
211 void StackAddrEscapeChecker::checkReturnedBlockCaptures(
212 const BlockDataRegion &B, CheckerContext &C)
const {
213 for (
const MemRegion *Region : getCapturedStackRegions(B, C)) {
214 if (isArcManagedBlock(Region, C) || isNotInCurrentFrame(Region, C))
216 ExplodedNode *N = C.generateNonFatalErrorNode();
219 if (!BT_capturedstackret)
220 BT_capturedstackret = llvm::make_unique<BuiltinBug>(
221 this,
"Address of stack-allocated memory is captured");
223 llvm::raw_svector_ostream Out(Buf);
224 SourceRange Range = genName(Out, Region, C.getASTContext());
225 Out <<
" is captured by a returned block";
227 llvm::make_unique<BugReport>(*BT_capturedstackret, Out.str(), N);
229 Report->addRange(Range);
230 C.emitReport(std::move(Report));
234 void StackAddrEscapeChecker::checkPreCall(
const CallEvent &Call,
235 CheckerContext &C)
const {
236 if (!ChecksEnabled[CK_StackAddrAsyncEscapeChecker])
238 if (!Call.isGlobalCFunction(
"dispatch_after") &&
239 !Call.isGlobalCFunction(
"dispatch_async"))
241 for (
unsigned Idx = 0, NumArgs = Call.getNumArgs(); Idx < NumArgs; ++Idx) {
242 if (
const BlockDataRegion *B = dyn_cast_or_null<BlockDataRegion>(
243 Call.getArgSVal(Idx).getAsRegion()))
244 checkAsyncExecutedBlockCaptures(*B, C);
248 void StackAddrEscapeChecker::checkPreStmt(
const ReturnStmt *RS,
249 CheckerContext &C)
const {
250 if (!ChecksEnabled[CK_StackAddrEscapeChecker])
258 SVal V = C.getSVal(RetE);
259 const MemRegion *R = V.getAsRegion();
263 if (
const BlockDataRegion *B = dyn_cast<BlockDataRegion>(R))
264 checkReturnedBlockCaptures(*B, C);
266 if (!isa<StackSpaceRegion>(R->getMemorySpace()) ||
267 isNotInCurrentFrame(R, C) || isArcManagedBlock(R, C))
274 RetE = Cleanup->getSubExpr();
280 if (
auto *ICE = dyn_cast<ImplicitCastExpr>(RetE)) {
281 if (isa<BlockDataRegion>(R) &&
282 ICE->getCastKind() == CK_CopyAndAutoreleaseBlockObject) {
287 EmitStackError(C, R, RetE);
290 void StackAddrEscapeChecker::checkEndFunction(
const ReturnStmt *RS,
291 CheckerContext &Ctx)
const {
292 if (!ChecksEnabled[CK_StackAddrEscapeChecker])
299 class CallBack :
public StoreManager::BindingsHandler {
307 CallBack(CheckerContext &CC) : Ctx(CC), CurSFC(CC.getStackFrame()) {}
309 bool HandleBinding(StoreManager &SMgr,
Store S,
const MemRegion *Region,
312 if (!isa<GlobalsSpaceRegion>(Region->getMemorySpace()))
314 const MemRegion *VR = Val.getAsRegion();
315 if (VR && isa<StackSpaceRegion>(VR->getMemorySpace()) &&
316 !isArcManagedBlock(VR, Ctx) && !isNotInCurrentFrame(VR, Ctx))
317 V.emplace_back(Region, VR);
323 State->getStateManager().getStoreManager().iterBindings(State->getStore(),
330 ExplodedNode *N = Ctx.generateNonFatalErrorNode(State);
335 BT_stackleak = llvm::make_unique<BuiltinBug>(
336 this,
"Stack address stored into global variable",
337 "Stack address was saved into a global variable. " 338 "This is dangerous because the address will become " 339 "invalid after returning from the function");
341 for (
const auto &
P : Cb.V) {
344 llvm::raw_svector_ostream Out(Buf);
345 SourceRange Range = genName(Out,
P.second, Ctx.getASTContext());
346 Out <<
" is still referred to by the ";
347 if (isa<StaticGlobalSpaceRegion>(
P.first->getMemorySpace()))
351 Out <<
" variable '";
352 const VarRegion *VR = cast<VarRegion>(
P.first->getBaseRegion());
353 Out << *VR->getDecl()
354 <<
"' upon returning to the caller. This will be a dangling reference";
355 auto Report = llvm::make_unique<BugReport>(*BT_stackleak, Out.str(), N);
357 Report->addRange(Range);
359 Ctx.emitReport(std::move(Report));
363 #define REGISTER_CHECKER(name) \ 364 void ento::register##name(CheckerManager &Mgr) { \ 365 StackAddrEscapeChecker *Chk = \ 366 Mgr.registerChecker<StackAddrEscapeChecker>(); \ 367 Chk->ChecksEnabled[StackAddrEscapeChecker::CK_##name] = true; \
A (possibly-)qualified type.
Defines the SourceManager interface.
bool isRecordType() const
SourceLocation getBeginLoc() const LLVM_READONLY
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
CompoundLiteralExpr - [C99 6.5.2.5].
const void * Store
Store - This opaque type encapsulates an immutable mapping from locations to values.
Represents an expression – generally a full-expression – that introduces cleanups to be run at the ...
Defines the clang::Expr interface and subclasses for C++ expressions.
SourceLocation getBeginLoc() const LLVM_READONLY
One of these records is kept for each identifier that is lexed.
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
SourceLocation getBeginLoc() const LLVM_READONLY
void print(raw_ostream &OS, const PrintingPolicy &Policy, const Twine &PlaceHolder=Twine(), unsigned Indentation=0) const
const clang::PrintingPolicy & getPrintingPolicy() const
Pepresents a block literal declaration, which is like an unnamed FunctionDecl.
This represents one expression.
ReturnStmt - This represents a return, optionally of an expression: return; return 4;...
unsigned getExpansionLineNumber(SourceLocation Loc, bool *Invalid=nullptr) const
Encodes a location in the source.
IdentifierInfo & get(StringRef Name)
Return the identifier token info for the specified named identifier.
ASTContext & getASTContext() const LLVM_READONLY
#define REGISTER_CHECKER(name)
Dataflow Directional Tag Classes.
ArrayRef< Capture > captures() const
SourceManager & getSourceManager()
SourceRange getSourceRange() const override LLVM_READONLY
Source range that this declaration covers.
SourceRange getSourceRange() const LLVM_READONLY
SourceLocation tokens are not useful in isolation - they are low level value objects created/interpre...
A trivial tuple used to represent a source range.
This class handles loading and caching of source files into memory.
Expr * IgnoreParens() LLVM_READONLY
IgnoreParens - Ignore parentheses.