vport: Better handle too-long network device names in vport_del().

The 'count' argument to strncpy_from_user() is supposed to include space
for the null terminator, so add it in.  Also, refuse names that have more
than IFNAMSIZ-1 characters outright, instead of truncating them.

diff --git a/datapath/vport.c b/datapath/vport.c
index ef4d7db..9ed7cd1 100644 (file)
--- a/datapath/vport.c
+++ b/datapath/vport.c
@@ -277,10 +277,13 @@ vport_del(const char __user *udevname)
        struct vport *vport;
        struct dp_port *dp_port;
        int err = 0;
+       int retval;
 
-       if (strncpy_from_user(devname, udevname, IFNAMSIZ - 1) < 0)
+       retval = strncpy_from_user(devname, udevname, IFNAMSIZ);
+       if (retval < 0)
                return -EFAULT;
-       devname[IFNAMSIZ - 1] = '\0';
+       else if (retval >= IFNAMSIZ)
+               return -ENAMETOOLONG;
 
        rtnl_lock();