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[lldb] Defend against infinite recursion in GetClassDescriptor #145396

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Merged
merged 3 commits into from
Jun 24, 2025
Merged

[lldb] Defend against infinite recursion in GetClassDescriptor #145396

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1da01ac
[lldb] Defend against infinite recursion in GetClassDescriptor
JDevlieghere Jun 23, 2025
c3508e7
Merge branch 'main' into rdar140293233
JDevlieghere Jun 23, 2025
69bb4e7
Use llvm::SmallPtrSet
JDevlieghere Jun 24, 2025
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21 changes: 15 additions & 6 deletions lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1505,15 +1505,24 @@ AppleObjCRuntimeV2::GetClassDescriptorFromISA(ObjCISA isa) {

ObjCLanguageRuntime::ClassDescriptorSP
AppleObjCRuntimeV2::GetClassDescriptor(ValueObject &valobj) {
ValueObjectSet seen;
return GetClassDescriptorImpl(valobj, seen);
}

ObjCLanguageRuntime::ClassDescriptorSP
AppleObjCRuntimeV2::GetClassDescriptorImpl(ValueObject &valobj,
ValueObjectSet &seen) {
seen.insert(&valobj);

ClassDescriptorSP objc_class_sp;
if (valobj.IsBaseClass()) {
ValueObject *parent = valobj.GetParent();
// if I am my own parent, bail out of here fast..
if (parent && parent != &valobj) {
ClassDescriptorSP parent_descriptor_sp = GetClassDescriptor(*parent);
if (parent_descriptor_sp)
return parent_descriptor_sp->GetSuperclass();
}
// Fail if there's a cycle in our parent chain.
if (!parent || seen.count(parent))
return nullptr;
if (ClassDescriptorSP parent_descriptor_sp =
GetClassDescriptorImpl(*parent, seen))
return parent_descriptor_sp->GetSuperclass();
return nullptr;
}
// if we get an invalid VO (which might still happen when playing around with
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5 changes: 5 additions & 0 deletions lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.h
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Expand Up @@ -20,6 +20,7 @@
#include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"

#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallSet.h"

class RemoteNXMapTable;

Expand Down Expand Up @@ -421,6 +422,10 @@ class AppleObjCRuntimeV2 : public AppleObjCRuntime {

lldb::addr_t GetISAHashTablePointer();

using ValueObjectSet = llvm::SmallPtrSet<ValueObject *, 8>;
ClassDescriptorSP GetClassDescriptorImpl(ValueObject &valobj,
ValueObjectSet &seen);

/// Update the generation count of realized classes. This is not an exact
/// count but rather a value that is incremented when new classes are realized
/// or destroyed. Unlike the count in gdb_objc_realized_classes, it will
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