drivers/char/tty_io.c: Avoid panic when no console is configured.

When no console is configured tty_open tries to call kref_get on a NULL
pointer, return ENODEV instead.

Signed-off-by: Will Newton <will.newton@gmail.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 59f472143f08..1412a8d1e58d 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1795,12 +1795,15 @@ retry_open:
         }
 #endif
         if (device == MKDEV(TTYAUX_MAJOR, 1)) {
-                driver = tty_driver_kref_get(console_device(&index));
-                if (driver) {
-                        /* Don't let /dev/console block */
-                        filp->f_flags |= O_NONBLOCK;
-                        noctty = 1;
-                        goto got_driver;
+                struct tty_driver *console_driver = console_device(&index);
+                if (console_driver) {
+                        driver = tty_driver_kref_get(console_driver);
+                        if (driver) {
+                                /* Don't let /dev/console block */
+                                filp->f_flags |= O_NONBLOCK;
+                                noctty = 1;
+                                goto got_driver;
+                        }
                 }
                 mutex_unlock(&tty_mutex);
                 return -ENODEV;