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Thread Safety Analysis: Fix DenseMap iterator invalidation UAF 

Rather than storing BeforeInfo in the DenseMap by value, this stores a
unique_ptr to it, so that we can keep a pointer to it live across
subsequent DenseMap insertions.

This change also removes the unique_ptr wrapper around BeforeVect
because now we're indirecting at a higher level.

llvm-svn: 253694
This commit is contained in:
Reid Kleckner 2015-11-20 19:08:30 +00:00
parent 0502e98c8a
commit 19ff5602da
1 changed files with 36 additions and 39 deletions
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75
clang/lib/Analysis/ThreadSafety.cpp
View File

@ -258,16 +258,15 @@ private:
typedef SmallVector<const ValueDecl*, 4> BeforeVect;
struct BeforeInfo {
BeforeInfo() : Vect(nullptr), Visited(false) { }
BeforeInfo(BeforeInfo &&O)
: Vect(std::move(O.Vect)), Visited(O.Visited)
{}
BeforeInfo() : Visited(0) {}
BeforeInfo(BeforeInfo &&O) : Vect(std::move(O.Vect)), Visited(O.Visited) {}
std::unique_ptr<BeforeVect> Vect;
int Visited;
BeforeVect Vect;
int Visited;
};
typedef llvm::DenseMap<const ValueDecl*, BeforeInfo> BeforeMap;
typedef llvm::DenseMap<const ValueDecl *, std::unique_ptr<BeforeInfo>>
BeforeMap;
typedef llvm::DenseMap<const ValueDecl*, bool> CycleMap;
public:
@ -276,6 +275,9 @@ public:
BeforeInfo* insertAttrExprs(const ValueDecl* Vd,
ThreadSafetyAnalyzer& Analyzer);
BeforeInfo *getBeforeInfoForDecl(const ValueDecl *Vd,
ThreadSafetyAnalyzer &Analyzer);
void checkBeforeAfter(const ValueDecl* Vd,
const FactSet& FSet,
ThreadSafetyAnalyzer& Analyzer,
@ -965,26 +967,27 @@ public:
BeforeSet::BeforeInfo* BeforeSet::insertAttrExprs(const ValueDecl* Vd,
ThreadSafetyAnalyzer& Analyzer) {
// Create a new entry for Vd.
auto& Entry = BMap.FindAndConstruct(Vd);
BeforeInfo* Info = &Entry.second;
BeforeVect* Bv = nullptr;
BeforeInfo *Info = nullptr;
{
// Keep InfoPtr in its own scope in case BMap is modified later and the
// reference becomes invalid.
std::unique_ptr<BeforeInfo> &InfoPtr = BMap[Vd];
if (!InfoPtr)
InfoPtr.reset(new BeforeInfo());
Info = InfoPtr.get();
}
for (Attr* At : Vd->attrs()) {
switch (At->getKind()) {
case attr::AcquiredBefore: {
auto *A = cast<AcquiredBeforeAttr>(At);
// Create a new BeforeVect for Vd if necessary.
if (!Bv) {
Bv = new BeforeVect;
Info->Vect.reset(Bv);
}
// Read exprs from the attribute, and add them to BeforeVect.
for (const auto *Arg : A->args()) {
CapabilityExpr Cp =
Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
if (const ValueDecl *Cpvd = Cp.valueDecl()) {
Bv->push_back(Cpvd);
Info->Vect.push_back(Cpvd);
auto It = BMap.find(Cpvd);
if (It == BMap.end())
insertAttrExprs(Cpvd, Analyzer);
@ -1001,20 +1004,8 @@ BeforeSet::BeforeInfo* BeforeSet::insertAttrExprs(const ValueDecl* Vd,
Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
if (const ValueDecl *ArgVd = Cp.valueDecl()) {
// Get entry for mutex listed in attribute
BeforeInfo* ArgInfo;
auto It = BMap.find(ArgVd);
if (It == BMap.end())
ArgInfo = insertAttrExprs(ArgVd, Analyzer);
else
ArgInfo = &It->second;
// Create a new BeforeVect if necessary.
BeforeVect* ArgBv = ArgInfo->Vect.get();
if (!ArgBv) {
ArgBv = new BeforeVect;
ArgInfo->Vect.reset(ArgBv);
}
ArgBv->push_back(Vd);
BeforeInfo *ArgInfo = getBeforeInfoForDecl(ArgVd, Analyzer);
ArgInfo->Vect.push_back(Vd);
}
}
break;
@ -1027,6 +1018,18 @@ BeforeSet::BeforeInfo* BeforeSet::insertAttrExprs(const ValueDecl* Vd,
return Info;
}
BeforeSet::BeforeInfo *
BeforeSet::getBeforeInfoForDecl(const ValueDecl *Vd,
ThreadSafetyAnalyzer &Analyzer) {
auto It = BMap.find(Vd);
BeforeInfo *Info = nullptr;
if (It == BMap.end())
Info = insertAttrExprs(Vd, Analyzer);
else
Info = It->second.get();
assert(Info && "BMap contained nullptr?");
return Info;
}
/// Return true if any mutexes in FSet are in the acquired_before set of Vd.
void BeforeSet::checkBeforeAfter(const ValueDecl* StartVd,
@ -1041,12 +1044,7 @@ void BeforeSet::checkBeforeAfter(const ValueDecl* StartVd,
if (!Vd)
return false;
BeforeSet::BeforeInfo* Info;
auto It = BMap.find(Vd);
if (It == BMap.end())
Info = insertAttrExprs(Vd, Analyzer);
else
Info = &It->second;
BeforeSet::BeforeInfo *Info = getBeforeInfoForDecl(Vd, Analyzer);
if (Info->Visited == 1)
return true;
@ -1054,13 +1052,12 @@ void BeforeSet::checkBeforeAfter(const ValueDecl* StartVd,
if (Info->Visited == 2)
return false;
BeforeVect* Bv = Info->Vect.get();
if (!Bv)
if (Info->Vect.empty())
return false;
InfoVect.push_back(Info);
Info->Visited = 1;
for (auto *Vdb : *Bv) {
for (auto *Vdb : Info->Vect) {
// Exclude mutexes in our immediate before set.
if (FSet.containsMutexDecl(Analyzer.FactMan, Vdb)) {
StringRef L1 = StartVd->getName();