linux-kernel - Re: [PATCH] drivers/s390/char/tty3270: Remove function callback casts

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Message-ID: <202006270853.C40CA89806@keescook>
Date:   Sat, 27 Jun 2020 09:10:56 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Oscar Carter <oscar.carter@....com>
Cc:     Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        kernel-hardening@...ts.openwall.com, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/s390/char/tty3270: Remove function callback casts

On Sat, Jun 27, 2020 at 02:54:17PM +0200, Oscar Carter wrote:
> In an effort to enable -Wcast-function-type in the top-level Makefile to
> support Control Flow Integrity builds, remove all the function callback
> casts.
> 
> To do this modify the function prototypes accordingly.
> 
> Signed-off-by: Oscar Carter <oscar.carter@....com>

Oh yes, the tasklets! I'd love to see this fixed correctly. (Which is to
say, modernize the API.) Romain hasn't had time to continue the work:
https://lore.kernel.org/kernel-hardening/20190929163028.9665-1-romain.perier@gmail.com/

Is this something you'd want to tackle?

> ---
>  drivers/s390/char/tty3270.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c
> index 98d7fc152e32..aec996de44d9 100644
> --- a/drivers/s390/char/tty3270.c
> +++ b/drivers/s390/char/tty3270.c
> @@ -556,8 +556,9 @@ tty3270_scroll_backward(struct kbd_data *kbd)
>   * Pass input line to tty.
>   */
>  static void
> -tty3270_read_tasklet(struct raw3270_request *rrq)
> +tty3270_read_tasklet(unsigned long data)
>  {
> +	struct raw3270_request *rrq = (struct raw3270_request *)data;

Regardless, this is correct as far as fixing the prototype.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook