im learning about windows API. I try to create a program that list all the file from start path "C:\*" and get hash of those file. It work very well on debug mode, but when i build release, CryptGetHashParam give me 234 (More data is available). Here is a code and the output:

#include<Windows.h>
#include<iostream>
#include<stdio.h>
#include<string.h>

#include "Header.h"

#pragma comment(lib,"Advapi32.lib")

using namespace std;

#define SAFE_FREE(block){free(block); block = NULL;}

int main() {
    WCHAR wStartPath[] = L"C:";
    WCHAR wFinalPath[MAX_PATH] = { NULL };
    
    ListFile(wStartPath);
}

void ListFile(WCHAR* wPath) {
    WIN32_FIND_DATAW wFindFileData = { 0 };
    HANDLE hFile = 0;
    WCHAR wFinalPath[MAX_PATH] = { 0 };
    WCHAR wSource[MAX_PATH] = { 0 };

    swprintf(wFinalPath, L"%s\\*", wPath);

    hFile = FindFirstFileW(wFinalPath, &wFindFileData);
    if (hFile == INVALID_HANDLE_VALUE) {
        cout << "ListFile: FindFirstFileW failed " << GetLastError() << endl;
    }
    BOOL Check = TRUE;
    while (Check) {
        if (!wcsncmp(L".", wFindFileData.cFileName, 1) || !wcsncmp(L"..", wFindFileData.cFileName, 2)) {
            Check = FindNextFileW(hFile, &wFindFileData);
            continue;
        }
        else {
            if (wFindFileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
                swprintf(wFinalPath, L"%s\\%s", wPath, wFindFileData.cFileName);
                //wcout << wFinalPath << endl;
                ListFile(wFinalPath);
            }
            else {
                swprintf(wFinalPath, L"%s\\%s", wPath, wFindFileData.cFileName);
                CheckFile(wFinalPath);
            }
        }
        Check = FindNextFileW(hFile, &wFindFileData);
    }
    if (hFile != NULL && hFile != INVALID_HANDLE_VALUE) {
        FindClose(hFile);
    }
}

int CheckFile(WCHAR * wPath) {
    HCRYPTPROV hProv = 0;
    HCRYPTHASH hHash = 0;
    HANDLE hFile = CreateFileW(wPath,               
        GENERIC_READ,
        0,
        NULL,
        OPEN_EXISTING,
        FILE_ATTRIBUTE_NORMAL,
        NULL);
    if (hFile == INVALID_HANDLE_VALUE) {
        wcout << "Check file: CreateFileW failed - " << GetLastError() << endl;
        return 0;
    }
    DWORD dwFileSize = GetFileSize(hFile, NULL);
    BYTE* bFileData = (BYTE*) malloc(dwFileSize 1);
    if (bFileData == NULL) {
        wcout << "Check file: malloc failed - " << endl;
        CloseHandle(hFile);
        return 0;
    }
    memset(bFileData, 0, dwFileSize);
    DWORD dwBytesRead = 0;
    if (!ReadFile(hFile, bFileData, dwFileSize, &dwBytesRead, NULL)) {
        SAFE_FREE(bFileData);
        CloseHandle(hFile);
        wcout << "Check file: ReadFile failed - " << GetLastError() << endl;
        return 0;
    }
    if (!CryptAcquireContextW(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)) {
        wcout << "Check file: CryptAcquireContextW failed - " << GetLastError() << endl;
        SAFE_FREE(bFileData);
        CloseHandle(hFile);
        return 0;
    }
    if (!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash)) {
        wcout << "Check file: CryptCreateHash failed - " << GetLastError() << endl;
        SAFE_FREE(bFileData);
        CryptReleaseContext(hProv, 0);
        CryptDestroyHash(hHash);
        CloseHandle(hFile);
        return 0;
    }
    if (!CryptHashData(hHash, bFileData, dwFileSize, 0)) {
        wcout << "Check file: CryptHashData failed - " << GetLastError() << endl;
        SAFE_FREE(bFileData);
        CryptReleaseContext(hProv, 0);
        CryptDestroyHash(hHash);
        CloseHandle(hFile);
        return 0;
    }
    BYTE bMD5Hash[16] = { 0 };
    DWORD dwHash,i ;
    string sHexStr;
    if (CryptGetHashParam(hHash, HP_HASHVAL, bMD5Hash, &dwHash, 0)) {
        for (i = 0; i < dwHash; i  ) {
            char tmp[3] = { 0 };
            sprintf(tmp, "x", bMD5Hash[i]);
            sHexStr.append(tmp);
        }
    }
    else {
        wcout << GetLastError() << endl;
    }
    wcout << wPath << ": " << sHexStr.c_str() << endl;
}

Debug output:

C:\$GetCurrent\Logs\PartnerSetupCompleteResult.log: 13015015dd907d28996153df14881252
C:\$GetCurrent\SafeOS\GetCurrentOOBE.dll: 90c7b320b95a37aa058b0d42c35aa7a8
C:\$GetCurrent\SafeOS\GetCurrentRollback.ini: 5cf0b461170777de13f6460bcc527db8
C:\$GetCurrent\SafeOS\PartnerSetupComplete.cmd: dd592f713b9944941b6670157d5bf706
C:\$GetCurrent\SafeOS\preoobe.cmd: 2f9537b7f7cb5b559ed6ec3694832fe6
C:\$GetCurrent\SafeOS\SetupComplete.cmd: 0582b19fa3b500db28f976ed33efa487

Release ouptut:

C:\$GetCurrent\Logs\PartnerSetupCompleteResult.log:
234
C:\$GetCurrent\SafeOS\GetCurrentOOBE.dll:
234
C:\$GetCurrent\SafeOS\GetCurrentRollback.ini:
234
C:\$GetCurrent\SafeOS\PartnerSetupComplete.cmd:
234
C:\$GetCurrent\SafeOS\preoobe.cmd:
234

What just happend there ?

CodePudding user response：

You're not initializing pdwDataLen, which is used as both input and output parameter:

[in, out] pdwDataLen

A pointer to a DWORD value specifying the size, in bytes, of the pbData buffer. When the function returns, the DWORD value contains the number of bytes stored in the buffer.

So initialize it:

    DWORD dwHash = sizeof(bMD5hash), i;