[PATCH AUTOSEL 5.1 049/141] serial: imx: fix locking in set_termios()

Sasha Levin
2019-07-19T04:31:41Z

From: Sergey Organov <sorganov@gmail.com>

[ 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>
---
drivers/tty/serial/imx.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index dff75dc94731..105512440f3f 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -383,6 +383,7 @@ 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);
@@ -391,6 +392,7 @@ 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;
@@ -400,6 +402,7 @@ 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;
@@ -1550,6 +1553,16 @@ 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
@@ -1593,16 +1606,6 @@ 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);
--
2.20.1