ttyprintk: Fix NULL pointer deref by setting tty_port ops after initializing port

tty_port_init() zeroes out the tty port, which means that we have to set the
ops pointer /after/, not before this call.  Otherwise, tty_port_open will crash
when it tries to deref ops, which is now a NULL pointer.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
index 4945bd3d18d0e9de294ba2f1fb8c996662820a39..d5d2e4a985aa8602ff75f840f6af7e963f68471d 100644 (file)
--- a/drivers/char/ttyprintk.c
+++ b/drivers/char/ttyprintk.c
@@ -179,7 +179,6 @@ static int __init ttyprintk_init(void)
 {
        int ret = -ENOMEM;
 
-       tpk_port.port.ops = &null_ops;
        mutex_init(&tpk_port.port_write_mutex);
 
        ttyprintk_driver = tty_alloc_driver(1,
@@ -190,6 +189,7 @@ static int __init ttyprintk_init(void)
                return PTR_ERR(ttyprintk_driver);
 
        tty_port_init(&tpk_port.port);
+       tpk_port.port.ops = &null_ops;
 
        ttyprintk_driver->driver_name = "ttyprintk";
        ttyprintk_driver->name = "ttyprintk";