WINAPI VirtualQueryEx - invalid handle - c++

Question

I am trying to read some pages of memory of a 32 bit process using VirtualQueryEx using Visual Studio 2012.
However when I run the program I get VirtualQueryEx Error 6: Invalid Handle. However there is no error with the handle itself [hProcess] and I am passing in the appropriate parameters. What could be it?
#include <windows.h>
#include <tlhelp32.h>
#include <tchar.h>
#include <stdio.h>
// Forward declarations:
BOOL GetProcessList( );
BOOL ListProcessModules( DWORD dwPID );
BOOL ListProcessThreads( DWORD dwOwnerPID );
void printError( TCHAR* msg );
int main( void )
{
GetProcessList( );
system("pause");
return 0;
}
BOOL GetProcessList( )
{
HANDLE hProcessSnap;
HANDLE hProcess;
PROCESSENTRY32 pe32;
DWORD dwPriorityClass;
// Take a snapshot of all processes in the system.
hProcessSnap = CreateToolhelp32Snapshot( TH32CS_SNAPPROCESS, 0 );
if( hProcessSnap == INVALID_HANDLE_VALUE )
{
printError( TEXT("CreateToolhelp32Snapshot (of processes)") );
return( FALSE );
}
// Set the size of the structure before using it.
pe32.dwSize = sizeof( PROCESSENTRY32 );
// Retrieve information about the first process,
// and exit if unsuccessful
if( !Process32First( hProcessSnap, &pe32 ) )
{
printError( TEXT("Process32First") ); // show cause of failure
CloseHandle( hProcessSnap ); // clean the snapshot object
return( FALSE );
}
// Now walk the snapshot of processes, and
// display information about each process in turn
do
{
//If the process name equals foo_process.exe
if (!_tcscmp(pe32.szExeFile, _T("foo_process.exe")))
{
hProcess = OpenProcess(PROCESS_VM_READ | PROCESS_QUERY_INFORMATION, false, pe32.th32ProcessID );
if( hProcess == NULL )
printError( TEXT("OpenProcess") );
unsigned char *addr = NULL;
MEMORY_BASIC_INFORMATION meminfo;
if (VirtualQueryEx(hProcess, addr, &meminfo, sizeof(meminfo)) == 0){
printError( TEXT("VirtualQueryEx") );
//return FALSE;
}
}
} while( Process32Next( hProcessSnap, &pe32 ) );
CloseHandle( hProcessSnap );
return( TRUE );
}
void printError( TCHAR* msg )
{
...
}
EDIT: Handle has value:
EDIT 2: More Info:
Windows 7 64bit platform.
Visual Studio 2012 (32 bit debugger) ran
as Administrator
Process is *32 (32bit)

Answer 1

unsigned char *addr = NULL;
You're asking VirtualQueryEx to Query address 0 which is not valid, causing the failure.