[PATCH v2] drivers/tty/serial: check the return value of uart_port_check()

Li Zhong
2022-08-26T08:36:38Z

uart_port_check() will return NULL pointer when state->uart_port is
NULL. Check the return value before dereference it to avoid
null-pointer-dereference error.

Signed-off-by: Li Zhong <floridsleeves@gmail.com>
---
drivers/tty/serial/serial_core.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 12c87cd201a7..760e177166cf 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -194,6 +194,9 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
unsigned long page;
int retval = 0;

+ if (!uport)
+ return -EIO;
+
if (uport->type == PORT_UNKNOWN)
return 1;

@@ -498,6 +501,8 @@ static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *termios;
int hw_stopped;

+ if (!uport)
+ return;
/*
* If we have no tty, termios, or the port does not exist,
* then we can't set the parameters for this port.
@@ -1045,6 +1050,8 @@ static int uart_get_lsr_info(struct tty_struct *tty,
struct uart_port *uport = uart_port_check(state);
unsigned int result;

+ if (!uport)
+ return -EIO;
result = uport->ops->tx_empty(uport);

/*
--
2.25.1