serial: don't use uninitialized value in uart_poll_init()

commit d0009a32c9e4e083358092f3c97e3c6e803a8930 upstream.

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@kernel.org>
Fixes: 5e227ef2aa38 (serial: uart_poll_init() should power on the UART)
Cc: stable@vger.kernel.org
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240805102046.307511-4-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 9967444eae10cb06f9597c0f4d7c6e393becdfcd..1d0e7b8514ccc102702a5bb9590c86f8277d7180 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2696,14 +2696,13 @@ 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);
@@ -2723,10 +2722,10 @@ 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;
 }