Reference binding to null pointer @ Binary::data()

[prigluchenie]

Default constructed Binary makes UB here

yaml-cpp/include/yaml-cpp/binary.h

Line 33 in eaf7205

return owned() ? &m_data[0] : m_unownedData;

m_data[0] is illegal for empty vector. Using vector::data() member is a proper way.

Clang UB sanitizer reports "Reference binding to null pointer" here.

[ljluestc]

#include <vector>
#include <iostream>

// Simplified version of yaml-cpp's Binary class (problematic)
class Binary {
    std::vector<unsigned char> m_data;

public:
    Binary() = default;  // Default constructor creates empty vector
    unsigned char* data() { return &m_data[0]; }  // UB when empty
    const unsigned char* data() const { return &m_data[0]; }  // UB when empty
    std::size_t size() const { return m_data.size(); }
};

int main() {
    Binary b;  // Default constructed, m_data is empty
    std::cout << "Size: " << b.size() << std::endl;
    unsigned char* ptr = b.data();  // UB: accessing m_data[0] on empty vector
    std::cout << "Data pointer: " << static_cast<void*>(ptr) << std::endl;
    return 0;
}

[SGSSGene]

@prigluchenie thank you for reporting! and thank you @ljluestc for the minimal example. #1482 provides a fix for this issue.