//=== MallocChecker.cpp - A malloc/free checker -------------------*- C++ -*--//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines malloc/free checker, which checks for potential memory
// leaks, double free, and use-after-free problems.
//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/GRState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/GRStateTrait.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
#include "llvm/ADT/ImmutableMap.h"
using namespace clang;
using namespace ento;
namespace {
class RefState {
enum Kind { AllocateUnchecked, AllocateFailed, Released, Escaped,
Relinquished } K;
const Stmt *S;
public:
RefState(Kind k, const Stmt *s) : K(k), S(s) {}
bool isAllocated() const { return K == AllocateUnchecked; }
//bool isFailed() const { return K == AllocateFailed; }
bool isReleased() const { return K == Released; }
//bool isEscaped() const { return K == Escaped; }
//bool isRelinquished() const { return K == Relinquished; }
bool operator==(const RefState &X) const {
return K == X.K && S == X.S;
}
static RefState getAllocateUnchecked(const Stmt *s) {
return RefState(AllocateUnchecked, s);
}
static RefState getAllocateFailed() {
return RefState(AllocateFailed, 0);
}
static RefState getReleased(const Stmt *s) { return RefState(Released, s); }
static RefState getEscaped(const Stmt *s) { return RefState(Escaped, s); }
static RefState getRelinquished(const Stmt *s) {
return RefState(Relinquished, s);
}
void Profile(llvm::FoldingSetNodeID &ID) const {
ID.AddInteger(K);
ID.AddPointer(S);
}
};
class RegionState {};
class MallocChecker : public Checker<eval::Call, check::DeadSymbols, check::EndPath, check::PreStmt<ReturnStmt>, check::Location,
check::Bind, eval::Assume> {
mutable llvm::OwningPtr<BuiltinBug> BT_DoubleFree;
mutable llvm::OwningPtr<BuiltinBug> BT_Leak;
mutable llvm::OwningPtr<BuiltinBug> BT_UseFree;
mutable llvm::OwningPtr<BuiltinBug> BT_UseRelinquished;
mutable llvm::OwningPtr<BuiltinBug> BT_BadFree;
mutable IdentifierInfo *II_malloc, *II_free, *II_realloc, *II_calloc;
public:
MallocChecker() : II_malloc(0), II_free(0), II_realloc(0), II_calloc(0) {}
bool evalCall(const CallExpr *CE, CheckerContext &C) const;
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
void checkEndPath(EndOfFunctionNodeBuilder &B, ExprEngine &Eng) const;
void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
const GRState *evalAssume(const GRState *state, SVal Cond,
bool Assumption) const;
void checkLocation(SVal l, bool isLoad, CheckerContext &C) const;
void checkBind(SVal location, SVal val, CheckerContext &C) const;
private:
static void MallocMem(CheckerContext &C, const CallExpr *CE);
static void MallocMemReturnsAttr(CheckerContext &C, const CallExpr *CE,
const OwnershipAttr* Att);
static const GRState *MallocMemAux(CheckerContext &C, const CallExpr *CE,
const Expr *SizeEx, SVal Init,
const GRState *state) {
return MallocMemAux(C, CE, state->getSVal(SizeEx), Init, state);
}
static const GRState *MallocMemAux(CheckerContext &C, const CallExpr *CE,
SVal SizeEx, SVal Init,
const GRState *state);
void FreeMem(CheckerContext &C, const CallExpr *CE) const;
void FreeMemAttr(CheckerContext &C, const CallExpr *CE,
const OwnershipAttr* Att) const;
const GRState *FreeMemAux(CheckerContext &C, const CallExpr *CE,
const GRState *state, unsigned Num, bool Hold) const;
void ReallocMem(CheckerContext &C, const CallExpr *CE) const;
static void CallocMem(CheckerContext &C, const CallExpr *CE);
static bool SummarizeValue(llvm::raw_ostream& os, SVal V);
static bool SummarizeRegion(llvm::raw_ostream& os, const MemRegion *MR);
void ReportBadFree(CheckerContext &C, SVal ArgVal, SourceRange range) const;
};
} // end anonymous namespace
typedef llvm::ImmutableMap<SymbolRef, RefState> RegionStateTy;
namespace clang {
namespace ento {
template <>
struct GRStateTrait<RegionState>
: public GRStatePartialTrait<RegionStateTy> {
static void *GDMIndex() { static int x; return &x; }
};
}
}
bool MallocChecker::evalCall(const CallExpr *CE, CheckerContext &C) const {
const GRState *state = C.getState();
const Expr *Callee = CE->getCallee();
SVal L = state->getSVal(Callee);
const FunctionDecl *FD = L.getAsFunctionDecl();
if (!FD)
return false;
ASTContext &Ctx = C.getASTContext();
if (!II_malloc)
II_malloc = &Ctx.Idents.get("malloc");
if (!II_free)
II_free = &Ctx.Idents.get("free");
if (!II_realloc)
II_realloc = &Ctx.Idents.get("realloc");
if (!II_calloc)
II_calloc = &Ctx.Idents.get("calloc");
if (FD->getIdentifier() == II_malloc) {
MallocMem(C, CE);
return true;
}
if (FD->getIdentifier() == II_free) {
FreeMem(C, CE);
return true;
}
if (FD->getIdentifier() == II_realloc) {
ReallocMem(C, CE);
return true;
}
if (FD->getIdentifier() == II_calloc) {
CallocMem(C, CE);
return true;
}
// Check all the attributes, if there are any.
// There can be multiple of these attributes.
bool rv = false;
if (FD->hasAttrs()) {
for (specific_attr_iterator<OwnershipAttr>
i = FD->specific_attr_begin<OwnershipAttr>(),
e = FD->specific_attr_end<OwnershipAttr>();
i != e; ++i) {
switch ((*i)->getOwnKind()) {
case OwnershipAttr::Returns: {
MallocMemReturnsAttr(C, CE, *i);
rv = true;
break;
}
case OwnershipAttr::Takes:
case OwnershipAttr::Holds: {
FreeMemAttr(C, CE, *i);
rv = true;
break;
}
default:
break;
}
}
}
return rv;
}
void MallocChecker::MallocMem(CheckerContext &C, const CallExpr *CE) {
const GRState *state = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(),
C.getState());
C.addTransition(state);
}
void MallocChecker::MallocMemReturnsAttr(CheckerContext &C, const CallExpr *CE,
const OwnershipAttr* Att) {
if (Att->getModule() != "malloc")
return;
OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
if (I != E) {
const GRState *state =
MallocMemAux(C, CE, CE->getArg(*I), UndefinedVal(), C.getState());
C.addTransition(state);
return;
}
const GRState *state = MallocMemAux(C, CE, UnknownVal(), UndefinedVal(),
C.getState());
C.addTransition(state);
}
const GRState *MallocChecker::MallocMemAux(CheckerContext &C,
const CallExpr *CE,
SVal Size, SVal Init,
const GRState *state) {
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
SValBuilder &svalBuilder = C.getSValBuilder();
// Set the return value.
SVal retVal = svalBuilder.getConjuredSymbolVal(NULL, CE, CE->getType(), Count);
state = state->BindExpr(CE, retVal);
// Fill the region with the initialization value.
state = state->bindDefault(retVal, Init);
// Set the region's extent equal to the Size parameter.
const SymbolicRegion *R = cast<SymbolicRegion>(retVal.getAsRegion());
DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
DefinedOrUnknownSVal DefinedSize = cast<DefinedOrUnknownSVal>(Size);
DefinedOrUnknownSVal extentMatchesSize =
svalBuilder.evalEQ(state, Extent, DefinedSize);
state = state->assume(extentMatchesSize, true);
assert(state);
SymbolRef Sym = retVal.getAsLocSymbol();
assert(Sym);
// Set the symbol's state to Allocated.
return state->set<RegionState>(Sym, RefState::getAllocateUnchecked(CE));
}
void MallocChecker::FreeMem(CheckerContext &C, const CallExpr *CE) const {
const GRState *state = FreeMemAux(C, CE, C.getState(), 0, false);
if (state)
C.addTransition(state);
}
void MallocChecker::FreeMemAttr(CheckerContext &C, const CallExpr *CE,
const OwnershipAttr* Att) const {
if (Att->getModule() != "malloc")
return;
for (OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
I != E; ++I) {
const GRState *state = FreeMemAux(C, CE, C.getState(), *I,
Att->getOwnKind() == OwnershipAttr::Holds);
if (state)
C.addTransition(state);
}
}
const GRState *MallocChecker::FreeMemAux(CheckerContext &C, const CallExpr *CE,
const GRState *state, unsigned Num,
bool Hold) const {
const Expr *ArgExpr = CE->getArg(Num);
SVal ArgVal = state->getSVal(ArgExpr);
DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(ArgVal);
// Check for null dereferences.
if (!isa<Loc>(location))
return state;
// FIXME: Technically using 'Assume' here can result in a path
// bifurcation. In such cases we need to return two states, not just one.
const GRState *notNullState, *nullState;
llvm::tie(notNullState, nullState) = state->assume(location);
// The explicit NULL case, no operation is performed.
if (nullState && !notNullState)
return nullState;
assert(notNullState);
// Unknown values could easily be okay
// Undefined values are handled elsewhere
if (ArgVal.isUnknownOrUndef())
return notNullState;
const MemRegion *R = ArgVal.getAsRegion();
// Nonlocs can't be freed, of course.
// Non-region locations (labels and fixed addresses) also shouldn't be freed.
if (!R) {
ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
return NULL;
}
R = R->StripCasts();
// Blocks might show up as heap data, but should not be free()d
if (isa<BlockDataRegion>(R)) {
ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
return NULL;
}
const MemSpaceRegion *MS = R->getMemorySpace();
// Parameters, locals, statics, and globals shouldn't be freed.
if (!(isa<UnknownSpaceRegion>(MS) || isa<HeapSpaceRegion>(MS))) {
// FIXME: at the time this code was written, malloc() regions were
// represented by conjured symbols, which are all in UnknownSpaceRegion.
// This means that there isn't actually anything from HeapSpaceRegion
// that should be freed, even though we allow it here.
// Of course, free() can work on memory allocated outside the current
// function, so UnknownSpaceRegion is always a possibility.
// False negatives are better than false positives.
ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
return NULL;
}
const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R);
// Various cases could lead to non-symbol values here.
// For now, ignore them.
if (!SR)
return notNullState;
SymbolRef Sym = SR->getSymbol();
const RefState *RS = state->get<RegionState>(Sym);
// If the symbol has not been tracked, return. This is possible when free() is
// called on a pointer that does not get its pointee directly from malloc().
// Full support of this requires inter-procedural analysis.
if (!RS)
return notNullState;
// Check double free.
if (RS->isReleased()) {
if (ExplodedNode *N = C.generateSink()) {
if (!BT_DoubleFree)
BT_DoubleFree.reset(
new BuiltinBug("Double free",
"Try to free a memory block that has been released"));
// FIXME: should find where it's freed last time.
BugReport *R = new BugReport(*BT_DoubleFree,
BT_DoubleFree->getDescription(), N);
C.EmitReport(R);
}
return NULL;
}
// Normal free.
if (Hold)
return notNullState->set<RegionState>(Sym, RefState::getRelinquished(CE));
return notNullState->set<RegionState>(Sym, RefState::getReleased(CE));
}
bool MallocChecker::SummarizeValue(llvm::raw_ostream& os, SVal V) {
if (nonloc::ConcreteInt *IntVal = dyn_cast<nonloc::ConcreteInt>(&V))
os << "an integer (" << IntVal->getValue() << ")";
else if (loc::ConcreteInt *ConstAddr = dyn_cast<loc::ConcreteInt>(&V))
os << "a constant address (" << ConstAddr->getValue() << ")";
else if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&V))
os << "the address of the label '" << Label->getLabel()->getName() << "'";
else
return false;
return true;
}
bool MallocChecker::SummarizeRegion(llvm::raw_ostream& os,
const MemRegion *MR) {
switch (MR->getKind()) {
case MemRegion::FunctionTextRegionKind: {
const FunctionDecl *FD = cast<FunctionTextRegion>(MR)->getDecl();
if (FD)
os << "the address of the function '" << FD << "'";
else
os << "the address of a function";
return true;
}
case MemRegion::BlockTextRegionKind:
os << "block text";
return true;
case MemRegion::BlockDataRegionKind:
// FIXME: where the block came from?
os << "a block";
return true;
default: {
const MemSpaceRegion *MS = MR->getMemorySpace();
switch (MS->getKind()) {
case MemRegion::StackLocalsSpaceRegionKind: {
const VarRegion *VR = dyn_cast<VarRegion>(MR);
const VarDecl *VD;
if (VR)
VD = VR->getDecl();
else
VD = NULL;
if (VD)
os << "the address of the local variable '" << VD->getName() << "'";
else
os << "the address of a local stack variable";
return true;
}
case MemRegion::StackArgumentsSpaceRegionKind: {
const VarRegion *VR = dyn_cast<VarRegion>(MR);
const VarDecl *VD;
if (VR)
VD = VR->getDecl();
else
VD = NULL;
if (VD)
os << "the address of the parameter '" << VD->getName() << "'";
else
os << "the address of a parameter";
return true;
}
case MemRegion::NonStaticGlobalSpaceRegionKind:
case MemRegion::StaticGlobalSpaceRegionKind: {
const VarRegion *VR = dyn_cast<VarRegion>(MR);
const VarDecl *VD;
if (VR)
VD = VR->getDecl();
else
VD = NULL;
if (VD) {
if (VD->isStaticLocal())
os << "the address of the static variable '" << VD->getName() << "'";
else
os << "the address of the global variable '" << VD->getName() << "'";
} else
os << "the address of a global variable";
return true;
}
default:
return false;
}
}
}
}
void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal,
SourceRange range) const {
if (ExplodedNode *N = C.generateSink()) {
if (!BT_BadFree)
BT_BadFree.reset(new BuiltinBug("Bad free"));
llvm::SmallString<100> buf;
llvm::raw_svector_ostream os(buf);
const MemRegion *MR = ArgVal.getAsRegion();
if (MR) {
while (const ElementRegion *ER = dyn_cast<ElementRegion>(MR))
MR = ER->getSuperRegion();
// Special case for alloca()
if (isa<AllocaRegion>(MR))
os << "Argument to free() was allocated by alloca(), not malloc()";
else {
os << "Argument to free() is ";
if (SummarizeRegion(os, MR))
os << ", which is not memory allocated by malloc()";
else
os << "not memory allocated by malloc()";
}
} else {
os << "Argument to free() is ";
if (SummarizeValue(os, ArgVal))
os << ", which is not memory allocated by malloc()";
else
os << "not memory allocated by malloc()";
}
EnhancedBugReport *R = new EnhancedBugReport(*BT_BadFree, os.str(), N);
R->addRange(range);
C.EmitReport(R);
}
}
void MallocChecker::ReallocMem(CheckerContext &C, const CallExpr *CE) const {
const GRState *state = C.getState();
const Expr *arg0Expr = CE->getArg(0);
DefinedOrUnknownSVal arg0Val
= cast<DefinedOrUnknownSVal>(state->getSVal(arg0Expr));
SValBuilder &svalBuilder = C.getSValBuilder();
DefinedOrUnknownSVal PtrEQ =
svalBuilder.evalEQ(state, arg0Val, svalBuilder.makeNull());
// Get the size argument. If there is no size arg then give up.
const Expr *Arg1 = CE->getArg(1);
if (!Arg1)
return;
// Get the value of the size argument.
DefinedOrUnknownSVal Arg1Val =
cast<DefinedOrUnknownSVal>(state->getSVal(Arg1));
// Compare the size argument to 0.
DefinedOrUnknownSVal SizeZero =
svalBuilder.evalEQ(state, Arg1Val,
svalBuilder.makeIntValWithPtrWidth(0, false));
// If the ptr is NULL and the size is not 0, the call is equivalent to
// malloc(size).
const GRState *stateEqual = state->assume(PtrEQ, true);
if (stateEqual && state->assume(SizeZero, false)) {
// Hack: set the NULL symbolic region to released to suppress false warning.
// In the future we should add more states for allocated regions, e.g.,
// CheckedNull, CheckedNonNull.
SymbolRef Sym = arg0Val.getAsLocSymbol();
if (Sym)
stateEqual = stateEqual->set<RegionState>(Sym, RefState::getReleased(CE));
const GRState *stateMalloc = MallocMemAux(C, CE, CE->getArg(1),
UndefinedVal(), stateEqual);
C.addTransition(stateMalloc);
}
if (const GRState *stateNotEqual = state->assume(PtrEQ, false)) {
// If the size is 0, free the memory.
if (const GRState *stateSizeZero = stateNotEqual->assume(SizeZero, true))
if (const GRState *stateFree =
FreeMemAux(C, CE, stateSizeZero, 0, false)) {
// Add the state transition to set input pointer argument to be free.
C.addTransition(stateFree);
// Bind the return value to UndefinedVal because it is now free.
C.addTransition(stateFree->BindExpr(CE, UndefinedVal(), true));
}
if (const GRState *stateSizeNotZero = stateNotEqual->assume(SizeZero,false))
if (const GRState *stateFree = FreeMemAux(C, CE, stateSizeNotZero,
0, false)) {
// FIXME: We should copy the content of the original buffer.
const GRState *stateRealloc = MallocMemAux(C, CE, CE->getArg(1),
UnknownVal(), stateFree);
C.addTransition(stateRealloc);
}
}
}
void MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE) {
const GRState *state = C.getState();
SValBuilder &svalBuilder = C.getSValBuilder();
SVal count = state->getSVal(CE->getArg(0));
SVal elementSize = state->getSVal(CE->getArg(1));
SVal TotalSize = svalBuilder.evalBinOp(state, BO_Mul, count, elementSize,
svalBuilder.getContext().getSizeType());
SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
C.addTransition(MallocMemAux(C, CE, TotalSize, zeroVal, state));
}
void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper,
CheckerContext &C) const
{
if (!SymReaper.hasDeadSymbols())
return;
const GRState *state = C.getState();
RegionStateTy RS = state->get<RegionState>();
RegionStateTy::Factory &F = state->get_context<RegionState>();
for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
if (SymReaper.isDead(I->first)) {
if (I->second.isAllocated()) {
if (ExplodedNode *N = C.generateNode()) {
if (!BT_Leak)
BT_Leak.reset(new BuiltinBug("Memory leak",
"Allocated memory never released. Potential memory leak."));
// FIXME: where it is allocated.
BugReport *R = new BugReport(*BT_Leak, BT_Leak->getDescription(), N);
C.EmitReport(R);
}
}
// Remove the dead symbol from the map.
RS = F.remove(RS, I->first);
}
}
C.generateNode(state->set<RegionState>(RS));
}
void MallocChecker::checkEndPath(EndOfFunctionNodeBuilder &B,
ExprEngine &Eng) const {
const GRState *state = B.getState();
RegionStateTy M = state->get<RegionState>();
for (RegionStateTy::iterator I = M.begin(), E = M.end(); I != E; ++I) {
RefState RS = I->second;
if (RS.isAllocated()) {
ExplodedNode *N = B.generateNode(state);
if (N) {
if (!BT_Leak)
BT_Leak.reset(new BuiltinBug("Memory leak",
"Allocated memory never released. Potential memory leak."));
BugReport *R = new BugReport(*BT_Leak, BT_Leak->getDescription(), N);
Eng.getBugReporter().EmitReport(R);
}
}
}
}
void MallocChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const {
const Expr *retExpr = S->getRetValue();
if (!retExpr)
return;
const GRState *state = C.getState();
SymbolRef Sym = state->getSVal(retExpr).getAsSymbol();
if (!Sym)
return;
const RefState *RS = state->get<RegionState>(Sym);
if (!RS)
return;
// FIXME: check other cases.
if (RS->isAllocated())
state = state->set<RegionState>(Sym, RefState::getEscaped(S));
C.addTransition(state);
}
const GRState *MallocChecker::evalAssume(const GRState *state, SVal Cond,
bool Assumption) const {
// If a symblic region is assumed to NULL, set its state to AllocateFailed.
// FIXME: should also check symbols assumed to non-null.
RegionStateTy RS = state->get<RegionState>();
for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
// If the symbol is assumed to NULL, this will return an APSInt*.
if (state->getSymVal(I.getKey()))
state = state->set<RegionState>(I.getKey(),RefState::getAllocateFailed());
}
return state;
}
// Check if the location is a freed symbolic region.
void MallocChecker::checkLocation(SVal l, bool isLoad,CheckerContext &C) const {
SymbolRef Sym = l.getLocSymbolInBase();
if (Sym) {
const RefState *RS = C.getState()->get<RegionState>(Sym);
if (RS && RS->isReleased()) {
if (ExplodedNode *N = C.generateNode()) {
if (!BT_UseFree)
BT_UseFree.reset(new BuiltinBug("Use dynamically allocated memory "
"after it is freed."));
BugReport *R = new BugReport(*BT_UseFree, BT_UseFree->getDescription(),
N);
C.EmitReport(R);
}
}
}
}
void MallocChecker::checkBind(SVal location, SVal val,CheckerContext &C) const {
// The PreVisitBind implements the same algorithm as already used by the
// Objective C ownership checker: if the pointer escaped from this scope by
// assignment, let it go. However, assigning to fields of a stack-storage
// structure does not transfer ownership.
const GRState *state = C.getState();
DefinedOrUnknownSVal l = cast<DefinedOrUnknownSVal>(location);
// Check for null dereferences.
if (!isa<Loc>(l))
return;
// Before checking if the state is null, check if 'val' has a RefState.
// Only then should we check for null and bifurcate the state.
SymbolRef Sym = val.getLocSymbolInBase();
if (Sym) {
if (const RefState *RS = state->get<RegionState>(Sym)) {
// If ptr is NULL, no operation is performed.
const GRState *notNullState, *nullState;
llvm::tie(notNullState, nullState) = state->assume(l);
// Generate a transition for 'nullState' to record the assumption
// that the state was null.
if (nullState)
C.addTransition(nullState);
if (!notNullState)
return;
if (RS->isAllocated()) {
// Something we presently own is being assigned somewhere.
const MemRegion *AR = location.getAsRegion();
if (!AR)
return;
AR = AR->StripCasts()->getBaseRegion();
do {
// If it is on the stack, we still own it.
if (AR->hasStackNonParametersStorage())
break;
// If the state can't represent this binding, we still own it.
if (notNullState == (notNullState->bindLoc(cast<Loc>(location),
UnknownVal())))
break;
// We no longer own this pointer.
notNullState =
notNullState->set<RegionState>(Sym,
RefState::getRelinquished(C.getStmt()));
}
while (false);
}
C.addTransition(notNullState);
}
}
}
void ento::registerMallocChecker(CheckerManager &mgr) {
mgr.registerChecker<MallocChecker>();
}