linux-kernel - Re: [PATCH v2 2/2] tty: fix compat TIOCGSERIAL checking wrong function ptr

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Date:   Tue, 25 Feb 2020 08:30:19 +0100
From:   Jiri Slaby <jslaby@...e.com>
To:     Eric Biggers <ebiggers@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v2 2/2] tty: fix compat TIOCGSERIAL checking wrong
 function ptr

On 24. 02. 20, 19:20, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> Commit 77654350306a ("take compat TIOC[SG]SERIAL treatment into
> tty_compat_ioctl()") changed the compat version of TIOCGSERIAL to start
> checking for the presence of the ->set_serial function pointer rather
> than ->get_serial.  This appears to be a copy-and-paste error, since
> ->get_serial is the function pointer that is called as well as the
> pointer that is checked by the non-compat version of TIOCGSERIAL.
> 
> Fix this by checking the correct function pointer.
> 
> Fixes: 77654350306a ("take compat TIOC[SG]SERIAL treatment into tty_compat_ioctl()")
> Cc: <stable@...r.kernel.org> # v4.20+
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>

Acked-by: Jiri Slaby <jslaby@...e.cz>

> ---
>  drivers/tty/tty_io.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index db4a13bc855ed6..5a6f36b391d95d 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -2734,7 +2734,7 @@ static int compat_tty_tiocgserial(struct tty_struct *tty,
>  	memset(&v, 0, sizeof(v));
>  	memset(&v32, 0, sizeof(v32));
>  
> -	if (!tty->ops->set_serial)
> +	if (!tty->ops->get_serial)
>  		return -ENOTTY;
>  	err = tty->ops->get_serial(tty, &v);
>  	if (!err) {
> 


-- 
js
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