linux-kernel - Re: [PATCH v8 1/4] ttynull: Always initialize console index to -1

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z9Gcg-iMMCAhLUJf@pathway.suse.cz>
Date: Wed, 12 Mar 2025 15:38:59 +0100
From: Petr Mladek <pmladek@...e.com>
To: adamsimonelli@...il.com
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jiri Slaby <jirislaby@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH v8 1/4] ttynull: Always initialize console index to -1

On Mon 2025-03-10 23:31:30, adamsimonelli@...il.com wrote:
> From: Adam Simonelli <adamsimonelli@...il.com>
> 
> This allows ttynull to be considered in console selection.

This is not true. It should be possible to register ttynull even
when .index == 0.

The .index is important only for drivers which support more devices,
e.g. the serial port or virtual terminal.

> 
> Suggested-by: Petr Mladek <pmladek@...e.com>
> Signed-off-by: Adam Simonelli <adamsimonelli@...il.com>
> ---
>  drivers/tty/ttynull.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/tty/ttynull.c b/drivers/tty/ttynull.c
> index 6b2f7208b564..d8b51edde628 100644
> --- a/drivers/tty/ttynull.c
> +++ b/drivers/tty/ttynull.c
> @@ -57,6 +57,7 @@ static struct tty_driver *ttynull_device(struct console *c, int *index)
>  static struct console ttynull_console = {
>  	.name = "ttynull",
>  	.device = ttynull_device,
> +	.index = -1,

There is only one "/dev/ttynull". And its index is initialized to "0".
At least it seems to be the last parameter in:

static int __init ttynull_init(void)
{
[...]
	tty_port_link_device(&ttynull_port, driver, 0);
[...]
}

So, I believe this it should be perfectly fine to keep the default "0"
here. Note that it is special for ttynull because it is only one...

IMHO, this patch adds more harm than good :-)

Best Regards,
Petr