linux-kernel - Re: [PATCH 1/2] tty: ldisc: Fix misuse of proc_dointvec "ldisc

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Date:   Tue, 25 Jun 2019 11:32:16 +0800
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Eiichi Tsukata <devel@...ukata.com>
Cc:     jslaby@...e.com, davem@...emloft.net, kuznet@....inr.ac.ru,
        yoshfuji@...ux-ipv6.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 1/2] tty: ldisc: Fix misuse of proc_dointvec
 "ldisc_autoload"

On Tue, Jun 25, 2019 at 12:08:00PM +0900, Eiichi Tsukata wrote:
> /proc/sys/dev/tty/ldisc_autoload assumes given value to be 0 or 1. Use
> proc_dointvec_minmax instead of proc_dointvec.
> 
> Fixes: 7c0cca7c847e "(tty: ldisc: add sysctl to prevent autoloading of ldiscs)"
> Signed-off-by: Eiichi Tsukata <devel@...ukata.com>
> ---
>  drivers/tty/tty_ldisc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
> index e38f104db174..a8ea7a35c94e 100644
> --- a/drivers/tty/tty_ldisc.c
> +++ b/drivers/tty/tty_ldisc.c
> @@ -863,7 +863,7 @@ static struct ctl_table tty_table[] = {
>  		.data		= &tty_ldisc_autoload,
>  		.maxlen		= sizeof(tty_ldisc_autoload),
>  		.mode		= 0644,
> -		.proc_handler	= proc_dointvec,
> +		.proc_handler	= proc_dointvec_minmax,
>  		.extra1		= &zero,
>  		.extra2		= &one,

Ah, nice catch.  But this really isn't an issue as if you use a bigger
value, things will not "break", right?

thanks,

greg k-h