xen/9pfs: fix two resource leaks on error paths, discovered by Coverity

CID: 1374836
Signed-off-by: NStefano Stabellini <sstabellini@kernel.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NGreg Kurz <groug@kaod.org>
CC: anthony.perard@citrix.com
CC: groug@kaod.org
CC: aneesh.kumar@linux.vnet.ibm.com

hw/9pfs/xen-9p-backend.c

@@ -332,12 +332,14 @@ static int xen_9pfs_connect(struct XenDevice *xendev)
         str = g_strdup_printf("ring-ref%u", i);
         if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
                                  &xen_9pdev->rings[i].ref) == -1) {
+            g_free(str);
             goto out;
         }
         g_free(str);
         str = g_strdup_printf("event-channel-%u", i);
         if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
                                  &xen_9pdev->rings[i].evtchn) == -1) {
+            g_free(str);
             goto out;
         }
         g_free(str);