Re: [PATCH v10 1/2] fork: extend clone3() to support setting a PID

[Oleg Nesterov <oleg@redhat.com>]

On 11/14, Adrian Reber wrote:
>
> @@ -2600,6 +2602,15 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
>  	if (err)
>  		return err;
>
> +	if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
> +		return -EINVAL;

so we need this to because copy_from_user() below writes into the
set_tid[MAX_PID_NS_LEVEL] on the caller's stack, then later alloc_pid()
does another "correct" check... We could simply shift that check here,
but probably this would be less clear, so I won't argue.

> @@ -2617,8 +2628,16 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
>  		.stack		= args.stack,
>  		.stack_size	= args.stack_size,
>  		.tls		= args.tls,
> +		.set_tid_size	= args.set_tid_size,
>  	};
...
> +	kargs->set_tid = kset_tid;

this looks a bit strange, you could simply do

		.set_tid_size   = args.set_tid_size,
		.set_tid	= kset_tid,

but this is really minor.

Looks good to me,

Reviewed-by: Oleg Nesterov <oleg@redhat.com>