Re: [PATCH v3 06/11] ntoskrnl.exe: Make sure thread handle has rights to retrieve the TID.

[Derek Lesho]

Signed-off-by: Derek Lesho

On Thu, Apr 11, 2019 at 2:27 PM Derek Lesho  wrote:
> Jacek says that duplicating and closing the sent handle in
> kernel_object_from_handle every time would add unecessary overhead.
>
> dlls/ntoskrnl.exe/ntoskrnl.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/dlls/ntoskrnl.exe/ntoskrnl.c b/dlls/ntoskrnl.exe/ntoskrnl.c
> index 80a6fa89f7..03f6d78759 100644
> --- a/dlls/ntoskrnl.exe/ntoskrnl.c
> +++ b/dlls/ntoskrnl.exe/ntoskrnl.c
> @@ -2500,6 +2500,7 @@ PEPROCESS WINAPI IoGetCurrentProcess(void)
>
> static void *create_thread_object( HANDLE handle )
>  {
> - NTSTATUS status;
> THREAD_BASIC_INFORMATION info;
> struct _KTHREAD *thread;
>
> @@ -2508,8 +2509,20 @@ static void *create_thread_object( HANDLE handle )
>      thread->header.Type = 6;
>      thread->header.WaitListHead.Blink = INVALID_HANDLE_VALUE; /* mark as
> kernel object */
> - if (!NtQueryInformationThread( handle, ThreadBasicInformation, &info,
>
> sizeof(info), NULL ))
> - if (!(status = NtQueryInformationThread( handle,
>
> ThreadBasicInformation, &info, sizeof(info), NULL )))
>          thread->id = info.ClientId;
> - else if (status == STATUS_ACCESS_DENIED)
> - {
> -
>    HANDLE info_handle;
> -
> -
>    DuplicateHandle( GetCurrentProcess(), handle,
>
> GetCurrentProcess(),
> -
>                &info_handle, THREAD_QUERY_LIMITED_INFORMATION,
>
> FALSE, 0);
> -
> -
>    if (!NtQueryInformationThread( handle, ThreadBasicInformation,
>
> &info, sizeof(info), NULL ))
> -
>        thread->id = info.ClientId;
> -
> -
>    NtClose( info_handle );
> -
>
> }
>
> thread->critical_region = FALSE;
>
> @@ -2539,7 +2552,7 @@ PRKTHREAD WINAPI KeGetCurrentThread(void)
>          HANDLE handle = GetCurrentThread();
>      /* FIXME: we shouldn't need it, GetCurrentThread() should be
>
> client thread already */
> -
>    if (GetCurrentThreadId() == request_thread) handle = OpenThread(
>
> 0, FALSE, client_tid );
> -
>    if (GetCurrentThreadId() == request_thread) handle = OpenThread(
>
> THREAD_QUERY_LIMITED_INFORMATION, FALSE, client_tid );
>      kernel_object_from_handle( handle, PsThreadType, (void**)&thread
>
> );
>          if (handle != GetCurrentThread()) NtClose( handle );
> --
> 2.20.1