Unexpected pointer wrapping when manually inserting LLVM modules

[MarcelHB]

Hallo again,

There is something I noticed. I made my project a standalone Phasar tool, and I preprocess LLVM IR code by making it feed to llvm::parseIRFile first, then doing some transformations, and then passing it to psr::ProjectIRDB#insert_module. For the next run, I was greeted by a double free error.

The cause is located here: https://github.com/secure-software-engineering/phasar/blob/master/lib/DB/ProjectIRDB.cpp#L706

I originally created the llvm::LLVMContext as a stack variable in my main and used that for parsing. So I suggest to change the signature of that method to something like:

void ProjectIRDB::insertModule(
  std::unique_ptr<llvm::Module> M, 
  std::unique_ptr<llvm::LLVMContext> C
);

So that I can create and move the required context pointer explicitly. For now, I do:

// Phasar cleans this up.
auto context = new llvm::LLVMContext;

That's Ok, but secretly wrapping M->getContext() into a unique pointer is a sneaky move. 😉

[pdschubert]

Thanks for your feedback. Yeah, you might be right. We have been running into problems when using the ProjectIRDB for more complex and exotic scenarios and therefore, are going to improve it. While doing so, we will certainly adjust the behavior and make the transfer in ownership explicit.