Subject: Re: [RFC PATCH v1 5/9] uaccess: Switch to copy_{to/from}_user_partial() when relevant

From: Alice Ryhl <[email-masked]>
Date: Mon, 27 Apr 2026 18:07:28 +0000

On Mon, Apr 27, 2026 at 07:13:46PM +0200, Christophe Leroy (CS GROUP) wrote:
> diff --git a/rust/helpers/uaccess.c b/rust/helpers/uaccess.c
> index 01de4fbbcc84..710e07cd60ae 100644
> --- a/rust/helpers/uaccess.c
> +++ b/rust/helpers/uaccess.c
> @@ -5,13 +5,13 @@
>  __rust_helper unsigned long
>  rust_helper_copy_from_user(void *to, const void __user *from, unsigned long n)
>  {
> -	return copy_from_user(to, from, n);
> +	return copy_from_user_partial(to, from, n);
>  }
>  
>  __rust_helper unsigned long
>  rust_helper_copy_to_user(void __user *to, const void *from, unsigned long n)
>  {
> -	return copy_to_user(to, from, n);
> +	return copy_to_user_partial(to, from, n);
>  }

No Rust code uses the return value for anything other than comparing it
with zero, so you can keep these as copy_[from|to]_user() without
issues.

Thanks, Alice