Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
plafosse wants to merge 1 commit into
base: dev
Choose a base branch
from
+28 −1
Open

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

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 28 additions & 1 deletion view/sharedcache/core/MachOProcessor.cpp
View file
Open in desktop
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)
Copy link
Contributor

@bdash bdash Mar 23, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It's probably best to use the same logic as MachoView::IsValidFunctionStart so we get consistent behavior. Ideally we'd share that code, but for whatever reason none of the Mach-O handling is shared at present.

Copy link
Member Author

@plafosse plafosse Mar 24, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

yeah that a good point I kind forgot that existed

{
// 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