[PATCH AUTOSEL 4.19 56/68] tty: fix NULL pointer issue when tty_port ops is not set

[Sasha Levin]

From: Fabien Dessenne <fabien.desse...@st.com>

[ Upstream commit f4e68d58cf2b20a581759bbc7228052534652673 ]

Unlike 'client_ops' which is initialized to 'default_client_ops', the
port operations 'ops' may be left to NULL.
Check the 'ops' value before checking the 'ops->x' value.

Signed-off-by: Fabien Dessenne <fabien.desse...@st.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Sasha Levin (Microsoft) <sas...@kernel.org>
---
 drivers/tty/tty_port.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index c699d41a2a48..81b23905c544 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -327,7 +327,7 @@ static void tty_port_shutdown(struct tty_port *port, struct 
tty_struct *tty)
                if (tty && C_HUPCL(tty))
                        tty_port_lower_dtr_rts(port);
 
-               if (port->ops->shutdown)
+               if (port->ops && port->ops->shutdown)
                        port->ops->shutdown(port);
        }
 out:
@@ -402,7 +402,7 @@ EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
 
 int tty_port_carrier_raised(struct tty_port *port)
 {
-       if (port->ops->carrier_raised == NULL)
+       if (!port->ops || !port->ops->carrier_raised)
                return 1;
        return port->ops->carrier_raised(port);
 }
@@ -419,7 +419,7 @@ EXPORT_SYMBOL(tty_port_carrier_raised);
 
 void tty_port_raise_dtr_rts(struct tty_port *port)
 {
-       if (port->ops->dtr_rts)
+       if (port->ops && port->ops->dtr_rts)
                port->ops->dtr_rts(port, 1);
 }
 EXPORT_SYMBOL(tty_port_raise_dtr_rts);
@@ -435,7 +435,7 @@ EXPORT_SYMBOL(tty_port_raise_dtr_rts);
 
 void tty_port_lower_dtr_rts(struct tty_port *port)
 {
-       if (port->ops->dtr_rts)
+       if (port->ops && port->ops->dtr_rts)
                port->ops->dtr_rts(port, 0);
 }
 EXPORT_SYMBOL(tty_port_lower_dtr_rts);
@@ -691,7 +691,7 @@ int tty_port_open(struct tty_port *port, struct tty_struct 
*tty,
 
        if (!tty_port_initialized(port)) {
                clear_bit(TTY_IO_ERROR, &tty->flags);
-               if (port->ops->activate) {
+               if (port->ops && port->ops->activate) {
                        int retval = port->ops->activate(port, tty);
                        if (retval) {
                                mutex_unlock(&port->mutex);
-- 
2.19.1