google / liburing_cpp

liburing_cpp

This project provides a idiomatic C++ wrapper for liburing.

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Copyright 2022 Google LLC

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liburing_cpp's Issues

Potential UB: No static alignment check in IoUringSQE::SetData(const T &data)

Expected Behavior

io_uring_cpp::IoUringSQE::SetData(const T &data) allows caller to pass any properly sized and trivially constructible type to be copied to the user data portion of an IO_URING SQE.

Actual Behavior

Potentially leads to UB where T is <= 8 bytes but T's alignment is more than alignment of uint64_t / 8 bytes.

The issue would be compiler and possibly process dependent.

Steps to Reproduce the Problem

1.Code leading to potential UB:

struct alignas(16) MyStruct {
  int a;
  char b;
};

int main() {
  MyStruct myData;
  myData.a = 10;
  myData.b = 'X';

  //code to initialize ring, sqe etc.

  // Call liburing_cpp's SetData()
  io_uring_cpp::IoUringSQE::SetData(myData); // Potential UB!

  return 0;
}

Specifications

• Version: Main Branch
• Platform: Linux / n.a

Potential Fix:

Add this static assert to SetData(const T &data) in file ./include/IoUringSQE.h:

static_assert(alignof(T) <= alignof(uint64_t), "T must have same alignment as uint64_t");