linux-kernel - Re: [PATCH v3 4/5] console: Avoid positive return code from unregister

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: <20200128044332.GA115889@google.com>
Date:   Tue, 28 Jan 2020 13:43:32 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/5] console: Avoid positive return code from
 unregister_console()

On (20/01/27 13:47), Andy Shevchenko wrote:
[..]
>  	res = _braille_unregister_console(console);
> -	if (res)
> +	if (res < 0)
>  		return res;
> +	if (res > 0)
> +		return 0;
>  
> -	res = 1;
> +	res = -ENODEV;
>  	console_lock();
>  	if (console_drivers == console) {
>  		console_drivers=console->next;
> @@ -2838,6 +2840,9 @@ int unregister_console(struct console *console)
>  	if (!res && (console->flags & CON_EXTENDED))
>  		nr_ext_console_drivers--;
>  
> +	if (res && !(console->flags & CON_ENABLED))
> +		res = 0;

Console is not on the console_drivers list. Why does !ENABLED case
require extra handling? What about the case when console is ENABLED
but still not registered?

I think that if the console is not on the list (was never registered)
then we can just bail out, without console_sysfs_notify(), etc. IOW,

	if (res) {
		console->flags &= ~CON_ENABLED; /* just in case */
		console_unlock();
		return res;
	}

	-ss