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Avoid creating functions at jump table entries in shared cache #8002

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Avoid creating functions at jump table entries in shared cache #8002

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29 changes: 28 additions & 1 deletion view/sharedcache/core/MachOProcessor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,30 @@ SharedCacheMachOProcessor::SharedCacheMachOProcessor(Ref<BinaryView> view, std::
}
}

static bool HeuristicIsAFunction(Platform* targetPlatform, std::shared_ptr<VirtualMemory> vm, uint64_t func)
{
// Very dumb heuristic which prevents us from creating function at jump tables
if (targetPlatform->GetArchitecture()->GetName() == "aarch64")
{
// disassemble then and ensure it's not a UDF instruction
uint32_t instruction = 0;
size_t instructionLength = 4;
vm->Read(&instruction, func, sizeof(instruction));
std::vector<InstructionTextToken> result;
targetPlatform->GetArchitecture()->GetInstructionText((uint8_t*)&instruction, func, instructionLength, result);
bool isUDF = false;
for (const auto& instructionText : result)
{
if (instructionText.type == BNInstructionTextTokenType::InstructionToken && instructionText.text == "udf")
{
// This is likely a jump table entry, skip creating a function here.
return false;
}
}
}
return true;
}

void SharedCacheMachOProcessor::ApplyHeader(const SharedCache& cache, SharedCacheMachOHeader& header)
{
auto typeLibraryFromName = [&](const std::string& name) -> Ref<TypeLibrary> {
Expand Down Expand Up @@ -52,7 +76,10 @@ void SharedCacheMachOProcessor::ApplyHeader(const SharedCache& cache, SharedCach
auto targetPlatform = m_view->GetDefaultPlatform();
auto functions = header.ReadFunctionTable(*m_vm);
for (const auto& func : functions)
m_view->AddFunctionForAnalysis(targetPlatform, func, false);
{
if (HeuristicIsAFunction(targetPlatform, m_vm, func))
m_view->AddFunctionForAnalysis(targetPlatform, func, false);
}
}

BulkSymbolModification bulkSymbolModification(m_view);
Expand Down