agent: network: Don't loop over a list being potentially modified

When the pod is destroyed, it removes all the routes and interfaces
previously setup. The list of routes and interfaces is maintained
by the agent, referring to list of pointers. When the agent tries
to rely on this list to remove routes and interfaces, the list is
updated by the code removing them, leading to weird situations
where the loop does not properly go over the expected items of the
list.

This commit duplicates the list of routes and interfaces as non
pointers, so that we make sure that any removal from the function
UpdateRoute() or UpdateInterface() will not result in modifying
the initial list being parsed.

Fixes kata-containers#226

Signed-off-by: Sebastien Boeuf <[email protected]>

network.go

@@ -508,19 +508,33 @@ func (s *sandbox) removeNetwork() error {
 	}
 	defer netHandle.Delete()
 
-	for _, route := range s.network.routes {
-		if err := s.removeRoute(netHandle, route); err != nil {
-			return grpcStatus.Errorf(codes.Internal, "Could not remove network route %v: %v",
-				route, err)
-		}
-	}
-
-	for _, iface := range s.network.ifaces {
-		if _, err := s.removeInterface(netHandle, iface); err != nil {
-			return grpcStatus.Errorf(codes.Internal, "Could not remove network interface %v: %v",
-				iface, err)
-		}
-	}
+	// Create a duplicate of the route list, with no pointers,
+	// otherwise this leads to a mix when routes are removed.
+	var routeList []pb.Route
+        for _, route := range s.network.routes {
+                routeList = append(routeList, *route)
+        }
+
+        for _, route := range routeList {
+                if err := s.removeRoute(netHandle, &route); err != nil {
+                        return grpcStatus.Errorf(codes.Internal, "Could not remove network route %v: %v",
+                                route, err)
+                }
+        }
+
+	// Create a duplicate of the interface list, with no pointers,
+	// otherwise this leads to a mix when interfaces are removed.
+        var ifaceList []pb.Interface
+        for _, iface := range s.network.ifaces {
+                ifaceList = append(ifaceList, *iface)
+        }
+
+        for _, iface := range ifaceList {
+                if _, err := s.removeInterface(netHandle, &iface); err != nil {
+                        return grpcStatus.Errorf(codes.Internal, "Could not remove network interface %v: %v",
+                                iface, err)
+                }
+        }
 
 	if err := removeDNS(s.network.dns); err != nil {
 		return grpcStatus.Errorf(codes.Internal, "Could not remove network DNS: %v", err)