Re: [PATCH v4 0/4] MR4761: ntdll: Implement NtContinueEx()

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about dlls/ntdll/unix/server.c:
> +{
> - /* NtContinueEx accepts both */
> - return NtContinueEx(context, (CONTINUE_OPTIONS *)(intptr_t)alertable);
>
> +}
> -
> -
>
> +/***********************************************************************
> -
> -
>          NtContinueEx  (NTDLL.@)
> - */
>
> +NTSTATUS WINAPI NtContinueEx( CONTEXT *context, CONTINUE_OPTIONS *options )
>  {
>      user_apc_t apc;
>      NTSTATUS status;
> - BOOLEAN alertable;
> -
> - if (options <= (CONTINUE_OPTIONS *)0xff)

Don't compare sentinel pointers without casting to unsigned integers.  Not only is comparison of invalid pointers an undefined behavior, but also do various compilers (e.g., MSVC) treat it as signed, which is incorrect here.

```suggestion:-0+0
    if ((ULONG_PTR)options <= 0xff)
```