xen/xenbus: Don't leak memory when unmapping the ring on HVM backend

commit c22fe519e7e2b94ad173e0ea3b89c1a7d8be8d00 upstream.

The commit ccc9d90a9a8b5c4ad7e9708ec41f75ff9e98d61d "xenbus_client:
Extend interface to support multi-page ring" removes the call to
free_xenballooned_pages() in xenbus_unmap_ring_vfree_hvm(), leaking a
page for every shared ring.

Only with backends running in HVM domains were affected.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 96b2011..658be6c 100644 (file)
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -814,8 +814,10 @@ static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 
        rv = xenbus_unmap_ring(dev, node->handles, node->nr_handles,
                               addrs);
-       if (!rv)
+       if (!rv) {
                vunmap(vaddr);
+               free_xenballooned_pages(node->nr_handles, node->hvm.pages);
+       }
        else
                WARN(1, "Leaking %p, size %u page(s)\n", vaddr,
                     node->nr_handles);