[Xen-devel] [PATCH] netback: don't store invalid vif pointer

["Jan Beulich" <JBeulich@xxxxxxxx>]

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@xxxxxxxx>

--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -404,6 +404,7 @@ static int backend_create_xenvif(struct 
        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 
                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;




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