serial: imx: fix locking in set_termios()

[ Upstream commit 4e828c3e09201512be5ee162393f334321f7cf01 ]

imx_uart_set_termios() called imx_uart_rts_active(), or
imx_uart_rts_inactive() before taking port->port.lock.

As a consequence, sport->port.mctrl that these functions modify
could have been changed without holding port->port.lock.

Moved locking of port->port.lock above the calls to fix the issue.

Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 0f67197..105de92 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -382,6 +382,7 @@ static void imx_uart_ucrs_restore(struct imx_port *sport,
 }
 #endif
 
+/* called with port.lock taken and irqs caller dependent */
 static void imx_uart_rts_active(struct imx_port *sport, u32 *ucr2)
 {
        *ucr2 &= ~(UCR2_CTSC | UCR2_CTS);
@@ -390,6 +391,7 @@ static void imx_uart_rts_active(struct imx_port *sport, u32 *ucr2)
        mctrl_gpio_set(sport->gpios, sport->port.mctrl);
 }
 
+/* called with port.lock taken and irqs caller dependent */
 static void imx_uart_rts_inactive(struct imx_port *sport, u32 *ucr2)
 {
        *ucr2 &= ~UCR2_CTSC;
@@ -399,6 +401,7 @@ static void imx_uart_rts_inactive(struct imx_port *sport, u32 *ucr2)
        mctrl_gpio_set(sport->gpios, sport->port.mctrl);
 }
 
+/* called with port.lock taken and irqs caller dependent */
 static void imx_uart_rts_auto(struct imx_port *sport, u32 *ucr2)
 {
        *ucr2 |= UCR2_CTSC;
@@ -1554,6 +1557,16 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
                old_csize = CS8;
        }
 
+       del_timer_sync(&sport->timer);
+
+       /*
+        * Ask the core to calculate the divisor for us.
+        */
+       baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
+       quot = uart_get_divisor(port, baud);
+
+       spin_lock_irqsave(&sport->port.lock, flags);
+
        if ((termios->c_cflag & CSIZE) == CS8)
                ucr2 = UCR2_WS | UCR2_SRST | UCR2_IRTS;
        else
@@ -1597,16 +1610,6 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
                        ucr2 |= UCR2_PROE;
        }
 
-       del_timer_sync(&sport->timer);
-
-       /*
-        * Ask the core to calculate the divisor for us.
-        */
-       baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
-       quot = uart_get_divisor(port, baud);
-
-       spin_lock_irqsave(&sport->port.lock, flags);
-
        sport->port.read_status_mask = 0;
        if (termios->c_iflag & INPCK)
                sport->port.read_status_mask |= (URXD_FRMERR | URXD_PRERR);