尝试移动指针 C++ 时的异常

我正在编写一个类来分配内存并存储一块内存占用的字节数。它的工作原理是这样的：我们分配大小为 n + 8/4 (x64, x32) 的内存，其中 n 是所需的字节数。在这 8 个字节中，我们写入了内存块占用的字节数。移位 8 个字节，使用。

代码第 44 行出现异常：

0x6F6C6C6540，“读取访问冲突”

#include <iostream>
#include <vector>
#include <malloc.h>

using namespace std;

#ifdef _WIN64
    #define SIZEBLOCK_BYTES 8
#else
    #define SIZEBLOCK_BYTES 4
#endif

template<class T>
T* move_pointer_right(void* ptr, size_t bytes)
{
    return reinterpret_cast<T*>(reinterpret_cast<bool*>(ptr) + bytes);
}

template<class T>
T* move_pointer_left(void* ptr, size_t bytes)
{
    return reinterpret_cast<T*>(reinterpret_cast<bool*>(ptr) - bytes);
}

class BSmartheap
{
private:
    vector<void*>infoheap;
public:
    void* allocate_block(size_t sizeBytes);
    void free_memory(void* blockMem);
    size_t size_block(void* blockMem);
};

size_t BSmartheap::size_block(void* blockMem)
{
    const size_t sizevec = infoheap.size();
    for (size_t x = 0; x < sizevec; x++)
    {
        if (&infoheap[x] == blockMem)
        {
            return move_pointer_left<size_t>(infoheap[x], SIZEBLOCK_BYTES)[0]; // exception here
        }
    }
    return 0;
}

void BSmartheap::free_memory(void* blockMem)
{
    const size_t sizevec = infoheap.size();
    for (size_t x = 0; x < sizevec; x++)
    {
        if (&infoheap[x] == blockMem)
        {
            free(move_pointer_left<void>(infoheap[x], SIZEBLOCK_BYTES));
            infoheap.erase(infoheap.begin() + x);
            return;
        }
    }
}

void* BSmartheap::allocate_block(size_t sizeBytes)
{
    if (sizeBytes == 0)
    {
        throw exception("Size is null");
    }
    void* newPtr = malloc(sizeBytes + SIZEBLOCK_BYTES);
    if (newPtr == nullptr)
    {
        throw exception("malloc return nullptr");
    }
    reinterpret_cast<size_t*>(newPtr)[0] = sizeBytes;
    newPtr = move_pointer_right<void>(newPtr, SIZEBLOCK_BYTES);
    infoheap.push_back(newPtr);
    return &infoheap[infoheap.size() - 1];
}

static BSmartheap heap;

int main()
{
    char* ptr = reinterpret_cast<char*>(heap.allocate_block(6));
    const char* str = "Hello";
    for (size_t x = 0; x < 6; x++)
    {
        ptr[x] = str[x];
    }

    cout << ptr << endl;
    cout << heap.size_block(ptr) << endl;

    heap.free_memory(ptr);
    system("pause");
    return 1;
}