linux-kernel - Re: [PATCH 03/13] serial: don't use uninitialized value in uart_poll

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Message-ID: <84af065c-b1a1-dc84-4c28-4596c3803fd2@linux.intel.com>
Date: Mon, 5 Aug 2024 17:28:05 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
    linux-serial <linux-serial@...r.kernel.org>, 
    LKML <linux-kernel@...r.kernel.org>, stable@...r.kernel.org, 
    Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH 03/13] serial: don't use uninitialized value in
 uart_poll_init()

On Mon, 5 Aug 2024, Jiri Slaby (SUSE) wrote:

> Coverity reports (as CID 1536978) that uart_poll_init() passes
> uninitialized pm_state to uart_change_pm(). It is in case the first 'if'
> takes the true branch (does "goto out;").
> 
> Fix this and simplify the function by simple guard(mutex). The code
> needs no labels after this at all. And it is pretty clear that the code
> has not fiddled with pm_state at that point.
> 
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
> Fixes: 5e227ef2aa38 (serial: uart_poll_init() should power on the UART)
> Cc: stable@...r.kernel.org
> Cc: Douglas Anderson <dianders@...omium.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  drivers/tty/serial/serial_core.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 3afe77f05abf..d63e9b636e02 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -2690,14 +2690,13 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
>  	int ret = 0;
>  
>  	tport = &state->port;
> -	mutex_lock(&tport->mutex);
> +
> +	guard(mutex)(&tport->mutex);
>  
>  	port = uart_port_check(state);
>  	if (!port || port->type == PORT_UNKNOWN ||
> -	    !(port->ops->poll_get_char && port->ops->poll_put_char)) {
> -		ret = -1;
> -		goto out;
> -	}
> +	    !(port->ops->poll_get_char && port->ops->poll_put_char))
> +		return -1;
>  
>  	pm_state = state->pm_state;
>  	uart_change_pm(state, UART_PM_STATE_ON);
> @@ -2717,10 +2716,10 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
>  		ret = uart_set_options(port, NULL, baud, parity, bits, flow);
>  		console_list_unlock();
>  	}
> -out:
> +
>  	if (ret)
>  		uart_change_pm(state, pm_state);
> -	mutex_unlock(&tport->mutex);
> +
>  	return ret;
>  }

This too needs #include.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

-- 
 i.