USB: cdc-acm: fix potential null-pointer dereference

Must check return value of tty_port_tty_get.

Cc: stable <stable@kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 00d809dfe84d..175637148962 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -533,6 +533,8 @@ static void acm_softint(struct work_struct *work)
         if (!ACM_READY(acm))
                 return;
         tty = tty_port_tty_get(&acm->port);
+        if (!tty)
+                return;
         tty_wakeup(tty);
         tty_kref_put(tty);
 }