线程中的分段错误C++

我正在尝试在C++中设置一个基本的线程类，但是当我尝试创建线程时遇到seg错误。以下是GDB报告的内容：

Program received signal SIGSEGV, Segmentation fault.
0x0000000000401b68 in StartThread (pFunction=
    0x401ad2 <FindPrimesThread(void*)>, pLimit=5000000) at Thread.cpp:35
35          state->mLimit = pLimit;

当我尝试这样称呼它时：

ThreadState *primesState = StartThread(FindPrimesThread, 5000000);

这是我的代码：

线程.hpp

#ifndef THREAD_HPP
#define THREAD_HPP
#include <pthread.h>
#include "Types.hpp"
typedef struct {
    ulong       mLimit;     // Upper limit of numbers to test 
    int         mStarted;   // True if the thread started successfully
    int         mExitCode;  // Thread exit code
    pthread_t   mThreadId;  // Thread ID
} ThreadState;
// Defines a type named ThreadFunction which is a pointer to a function with void * as the parameter and
// void * as the return value.
typedef void *(*ThreadFunction)(void *);
ThreadState *StartThread
    (
    ThreadFunction const pFunction,  // Pointer to the thread function
    ulong const          pLimit      // Upper limit of numbers to test
    );
#endif

螺纹.cpp

#include "Amicable.hpp"
#include "Keith.hpp"
#include "Main.hpp"
#include "Prime.hpp"
#include "Thread.hpp"
ThreadState *StartThread
    (
    ThreadFunction const pFunction,  // Pointer to the thread function
    ulong const          pLimit      // Upper limit of numbers to test
    ) {
        ThreadState *state;
        state->mLimit = pLimit;
        pthread_t threadId;
        state->mStarted = pthread_create(&threadId, NULL, pFunction, (void *)state);
        if(state->mStarted == 0){
            state->mThreadId = threadId;
        }
        return state;
    }

知道这里出了什么问题吗？