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

[ Upstream commit d0009a32c9e4e083358092f3c97e3c6e803a8930 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 3fb55f46a89149e4a303182ddc5cfd30cf428e1c..5d5570bebfeb611cdb2eed505895091a74ef26d6 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2694,14 +2694,13 @@ 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);
@@ -2721,10 +2720,10 @@ 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;
 }