我正在尝试从ntdll调用函数LdrLoadDll的想法来编写LoadLibrary函数的替代方法。此函数需要以UNICODE_STRING格式将要加载的dll文件作为参数。我真的无法弄清我在做什么错(字符串似乎已正确初始化),但是当调用LdrLoadDll时,出现以下错误:
“ Test.exe”(NTDLL.DLL)中未处理的异常:0xC0000005:访问冲突。
我为此测试使用Visual C ++ 6.0,并且我使用的是Windows 7 64位。
我在此处发布完整代码,在此先感谢您的任何帮助:
#include <Windows.h>
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->Buffer. The length of source is assigned to
* target->Length and target->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->Buffer = (PWSTR) source))
{
unsigned int length = lstrlenW(source) * sizeof(WCHAR);
if (length > 0xfffc)
length = 0xfffc;
target->Length = length;
target->MaximumLength = target->Length + sizeof(WCHAR);
}
else target->Length = target->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(&usDllFile, WideStr); //Initialize UNICODE_STRING for LdrLoadDll function
::SysFreeString(WideStr);
NTSTATUS result = _LdrLoadDll(NULL, LOAD_WITH_ALTERED_SEARCH_PATH, &usDllFile,0); //Error on this line!
return result;
}
void main()
{
LoadDll("Kernel32.dll");
}
在_LdrLoadDll(NULL,LOAD_WITH_ALTERED_SEARCH_PATH,&usDllFile,0);最后一个参数不能为零
您不能在调用_LdrLoadDll之前调用SysFreeString,因为usDllFile.buffer参数指向此字符串