Patch "serial: don't use uninitialized value in uart_poll_init()" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     serial-don-t-use-uninitialized-value-in-uart_poll_in.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d359c7c35d2fd925b184b57b22c1cf7afe95bbd5
Author: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
Date:   Mon Aug 5 12:20:36 2024 +0200

    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@xxxxxxxxxx>
    Fixes: 5e227ef2aa38 (serial: uart_poll_init() should power on the UART)
    Cc: stable@xxxxxxxxxxxxxxx
    Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
    Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
    Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240805102046.307511-4-jirislaby@xxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 3fb55f46a8914..5d5570bebfeb6 100644
--- 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;
 }