tty: Make get_current_tty use a kref

We now return a kref covered tty reference. That ensures the tty structure
doesn't go away when you have a return from get_current_tty. This is not
enough to protect you from most of the resources being freed behind your
back - yet.

[Updated to include fixes for SELinux problems found by Andrew Morton and
 an s390 leak found while debugging the former]

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

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/s390/char/fs3270.c b/drivers/s390/char/fs3270.c
index d18e6d2e0b49..3ef5425d0eb8 100644
--- a/drivers/s390/char/fs3270.c
+++ b/drivers/s390/char/fs3270.c
@@ -430,11 +430,12 @@ fs3270_open(struct inode *inode, struct file *filp)
                 mutex_lock(&tty_mutex);
                 tty = get_current_tty();
                 if (!tty || tty->driver->major != IBM_TTY3270_MAJOR) {
-                        mutex_unlock(&tty_mutex);
+                        tty_kref_put(tty);
                         rc = -ENODEV;
                         goto out;
                 }
                 minor = tty->index + RAW3270_FIRSTMINOR;
+                tty_kref_put(tty);
                 mutex_unlock(&tty_mutex);
         }
         /* Check if some other program is already using fullscreen mode. */