[PATCH] tty: fix NULL ptr dereference

[Jiri Slaby]

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/tty/tty_io.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index f89939922050..160f320e0d2c 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1255,6 +1255,7 @@ static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *
 static int tty_reopen(struct tty_struct *tty)
 {
 	struct tty_driver *driver = tty->driver;
+	int ret = 0;
 
 	if (driver->type == TTY_DRIVER_TYPE_PTY &&
 	    driver->subtype == PTY_TYPE_MASTER)
@@ -1268,10 +1269,12 @@ static int tty_reopen(struct tty_struct *tty)
 
 	tty->count++;
 
+	tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT);
 	if (!tty->ldisc)
-		return tty_ldisc_reinit(tty, tty->termios.c_line);
+		ret = tty_ldisc_reinit(tty, tty->termios.c_line);
+	tty_ldisc_unlock(tty);
 
-	return 0;
+	return ret;
 }
 
 /**
-- 
2.18.0


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