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POOpenProcess handle invalid for ReadProcessMemory
 

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    <p>I've made this simple class to open a process and read memory from it: The problem is when I call <code>ReadDWORD</code> with any memory address <code>ReadProcessMemory</code> fails with error code 6: <code>ERROR_INVALID_HANDLE, The handle is invalid</code>. And I can't figure out what I'm doing wrong.</p> <p>If I put the <code>OpenProcess</code> part in the <code>ReadDWORD</code> function it works fine. Is there something wrong with how I store the handle? Why does it become invalid before I use it?</p> <p><strong>Memory.h</strong></p> <pre><code>#ifndef MEMORY_H #define MEMORY_H #include &lt;windows.h&gt; #include &lt;psapi.h&gt; #pragma comment(lib, "psapi.lib") #include &lt;iostream&gt; class Memory { public: Memory(); Memory(DWORD offset); ~Memory(); DWORD ReadDWORD(DWORD addr); private: HANDLE m_hProc; DWORD m_Offset; }; #endif </code></pre> <p><strong>Memory.cpp</strong></p> <pre><code>#include "Memory.h" Memory::Memory() { Memory(0); } Memory::Memory(DWORD offset) { m_hProc = OpenProcess(PROCESS_VM_READ | PROCESS_QUERY_INFORMATION, false, 5444); // 5444 is the PID of a process I'm testing this with m_Offset = offset; } Memory::~Memory() { CloseHandle(m_hProc); } DWORD Memory::ReadDWORD(DWORD addr) { // Optional memory offset addr += m_Offset; DWORD value = -1; int result = ReadProcessMemory(m_hProc, (LPVOID)addr, &amp;value, sizeof(DWORD), NULL); if (result == 0) std::cout &lt;&lt; "ReadProcessMemory error: " &lt;&lt; GetLastError() &lt;&lt; std::endl; return value; } </code></pre>
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    1. COwhat is the `m_hProc` value? there is a chance that OpenProcess fails in `Memory::Memory` ctor. Also note that you can't just read random addresses of remote processes, typically correct virtual addresses are passed somehow. e.g. via IPC. Finally, hardcoding PID is not a good idea, you'll have to change it everytime you restard you testing app.
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    2. COI've checked m_hProc in Memory::Memory and it doesn't fail. In ReadDWORD m_hProc is different to what it is in Memory::Memory.
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