Databases
StackOverflow2013
Postsdbo
POLdrLoadDll problem
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POLdrLoadDll problem
    primarykey
    data
    text
    <p>I am trying to code an alternative to LoadLibrary function, based on the idea of calling the function LdrLoadDll from ntdll. This function needs as a parameter the dll file to load, in a UNICODE_STRING format. I really can't get what I am doing wrong here (string seems to be correctly initialized), but when LdrLoadDll is called, I get the following error:</p> <p>Unhandled exception in "Test.exe" (NTDLL.DLL): 0xC0000005: Access Violation.</p> <p>I use Visual C++ 6.0 for this test, and I am using Windows 7 64 bit.</p> <p>I post full code here, thanks in advance for any help:</p> <pre><code>#include &lt;Windows.h&gt; typedef LONG NTSTATUS; //To be used with VC++ 6, since NTSTATUS type is not defined typedef struct _UNICODE_STRING { //UNICODE_STRING structure USHORT Length; USHORT MaximumLength; PWSTR Buffer; } UNICODE_STRING; typedef UNICODE_STRING *PUNICODE_STRING; typedef NTSTATUS (WINAPI *fLdrLoadDll) //LdrLoadDll function prototype ( IN PWCHAR PathToFile OPTIONAL, IN ULONG Flags OPTIONAL, IN PUNICODE_STRING ModuleFileName, OUT PHANDLE ModuleHandle ); /************************************************************************** * RtlInitUnicodeString (NTDLL.@) * * Initializes a buffered unicode string. * * RETURNS * Nothing. * * NOTES * Assigns source to target-&gt;Buffer. The length of source is assigned to * target-&gt;Length and target-&gt;MaximumLength. If source is NULL the length * of source is assumed to be 0. */ void WINAPI RtlInitUnicodeString( PUNICODE_STRING target, /* [I/O] Buffered unicode string to be initialized */ PCWSTR source) /* [I] '\0' terminated unicode string used to initialize target */ { if ((target-&gt;Buffer = (PWSTR) source)) { unsigned int length = lstrlenW(source) * sizeof(WCHAR); if (length &gt; 0xfffc) length = 0xfffc; target-&gt;Length = length; target-&gt;MaximumLength = target-&gt;Length + sizeof(WCHAR); } else target-&gt;Length = target-&gt;MaximumLength = 0; } NTSTATUS LoadDll( LPCSTR lpFileName) { HMODULE hmodule = GetModuleHandleA("ntdll.dll"); fLdrLoadDll _LdrLoadDll = (fLdrLoadDll) GetProcAddress ( hmodule, "LdrLoadDll" ); int AnsiLen = lstrlenA(lpFileName); BSTR WideStr = SysAllocStringLen(NULL, AnsiLen); ::MultiByteToWideChar(CP_ACP, 0, lpFileName, AnsiLen, WideStr, AnsiLen); UNICODE_STRING usDllFile; RtlInitUnicodeString(&amp;usDllFile, WideStr); //Initialize UNICODE_STRING for LdrLoadDll function ::SysFreeString(WideStr); NTSTATUS result = _LdrLoadDll(NULL, LOAD_WITH_ALTERED_SEARCH_PATH, &amp;usDllFile,0); //Error on this line! return result; } void main() { LoadDll("Kernel32.dll"); } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USViotto01
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. POLdrLoadDll problem
      1. USMaximus
      1. VTFavorite
    1. COdo you know which line causes the access violation?
      singulars
      1. POLdrLoadDll problem
      1. USdsolimano
    2. COYeah, I wrote it on the code above: NTSTATUS result = _LdrLoadDll(NULL, LOAD_WITH_ALTERED_SEARCH_PATH, &usDllFile,0); //Error on this line!
      singulars
      1. POLdrLoadDll problem
      1. USViotto01
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload