serial: fix NULL pointer dereference

If kzalloc() or alloc_tty_driver() fails, we call:
    put_tty_driver(normal = NULL).

Then:
    put_tty_driver -> tty_driver_kref_put -> kref_put(&NULL->kref, ...)

Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 10 deletions

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index dcc72444e8e..885eabe552c 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -2344,7 +2344,7 @@ static const struct tty_operations uart_ops = {
  */
 int uart_register_driver(struct uart_driver *drv)
 {
-        struct tty_driver *normal = NULL;
+        struct tty_driver *normal;
         int i, retval;
 
         BUG_ON(drv->state);
@@ -2354,13 +2354,12 @@ int uart_register_driver(struct uart_driver *drv)
          * we have a large number of ports to handle.
          */
         drv->state = kzalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);
-        retval = -ENOMEM;
         if (!drv->state)
                 goto out;
 
-        normal  = alloc_tty_driver(drv->nr);
+        normal = alloc_tty_driver(drv->nr);
         if (!normal)
-                goto out;
+                goto out_kfree;
 
         drv->tty_driver = normal;
 
@@ -2393,12 +2392,14 @@ int uart_register_driver(struct uart_driver *drv)
         }
 
         retval = tty_register_driver(normal);
- out:
-        if (retval < 0) {
-                put_tty_driver(normal);
-                kfree(drv->state);
-        }
-        return retval;
+        if (retval >= 0)
+                return retval;
+
+        put_tty_driver(normal);
+out_kfree:
+        kfree(drv->state);
+out:
+        return -ENOMEM;
 }
 
 /**