netback: don't store invalid vif pointer

When xenvif_alloc() fails, it returns a non-NULL error indicator. To
avoid eventual races, we shouldn't store that into struct backend_info
as readers of it only check for NULL.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index fab0d4b42f58..d44cd19169bd 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -404,6 +404,7 @@ static int backend_create_xenvif(struct backend_info *be)
         int err;
         long handle;
         struct xenbus_device *dev = be->dev;
+        struct xenvif *vif;
 
         if (be->vif != NULL)
                 return 0;
@@ -414,13 +415,13 @@ static int backend_create_xenvif(struct backend_info *be)
                 return (err < 0) ? err : -EINVAL;
         }
 
-        be->vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
-        if (IS_ERR(be->vif)) {
-                err = PTR_ERR(be->vif);
-                be->vif = NULL;
+        vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
+        if (IS_ERR(vif)) {
+                err = PTR_ERR(vif);
                 xenbus_dev_fatal(dev, err, "creating interface");
                 return err;
         }
+        be->vif = vif;
 
         kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
         return 0;