Local users able to send the NULL arg argument to kbd_ioctl(), which could cause kernel crash


diff --git a/keyboard.c 
b/keyboard.c
index ba0e4f9..3ec16b1 100644
--- a/keyboard.c
+++ b/keyboard.c
@@ -456,6 +456,8 @@ int kbd_ioctl(struct kbd_data *kbd, unsigned int cmd, unsigned long arg)
        int perm;
 
        argp = (void __user *)arg;
+       if( !argp )
+               return -EFAULT;
 
        /*
         * To have permissions to do most of the vt ioctls, we either have