mlxsw: spectrum_router: Update nexthop RIF on update

The function mlxsw_sp_nexthop_rif_update() walks the list of nexthops
associated with a RIF, and updates the corresponding entries in the
switch. It is used in particular when a tunnel underlay netdevice moves
to a different VRF, and all the nexthops are migrated over to a new RIF.
The problem is that each nexthop holds a reference to its RIF, and that
is not updated. So after the old RIF is gone, further activity on these
nexthops (such as downing the underlay netdevice) dereferences a
dangling pointer.

Fix the issue by updating rif of impacted nexthops before calling
mlxsw_sp_nexthop_rif_update().

Fixes: 0c5f1cd ("mlxsw: spectrum_router: Generalize __mlxsw_sp_ipip_entry_update_tunnel()")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -1370,8 +1370,9 @@ static void mlxsw_sp_netdevice_ipip_ol_down_event(struct mlxsw_sp *mlxsw_sp,
 		mlxsw_sp_ipip_entry_ol_down_event(mlxsw_sp, ipip_entry);
 }
 
-static void mlxsw_sp_nexthop_rif_update(struct mlxsw_sp *mlxsw_sp,
-					struct mlxsw_sp_rif *rif);
+static void mlxsw_sp_nexthop_rif_migrate(struct mlxsw_sp *mlxsw_sp,
+					 struct mlxsw_sp_rif *old_rif,
+					 struct mlxsw_sp_rif *new_rif);
 static int
 mlxsw_sp_ipip_entry_ol_lb_update(struct mlxsw_sp *mlxsw_sp,
 				 struct mlxsw_sp_ipip_entry *ipip_entry,
@@ -1389,17 +1390,18 @@ mlxsw_sp_ipip_entry_ol_lb_update(struct mlxsw_sp *mlxsw_sp,
 		return PTR_ERR(new_lb_rif);
 	ipip_entry->ol_lb = new_lb_rif;
 
-	if (keep_encap) {
-		list_splice_init(&old_lb_rif->common.nexthop_list,
-				 &new_lb_rif->common.nexthop_list);
-		mlxsw_sp_nexthop_rif_update(mlxsw_sp, &new_lb_rif->common);
-	}
+	if (keep_encap)
+		mlxsw_sp_nexthop_rif_migrate(mlxsw_sp, &old_lb_rif->common,
+					     &new_lb_rif->common);
 
 	mlxsw_sp_rif_destroy(&old_lb_rif->common);
 
 	return 0;
 }
 
+static void mlxsw_sp_nexthop_rif_update(struct mlxsw_sp *mlxsw_sp,
+					struct mlxsw_sp_rif *rif);
+
 /**
  * Update the offload related to an IPIP entry. This always updates decap, and
  * in addition to that it also:
@@ -3560,6 +3562,18 @@ static void mlxsw_sp_nexthop_rif_update(struct mlxsw_sp *mlxsw_sp,
 	}
 }
 
+static void mlxsw_sp_nexthop_rif_migrate(struct mlxsw_sp *mlxsw_sp,
+					 struct mlxsw_sp_rif *old_rif,
+					 struct mlxsw_sp_rif *new_rif)
+{
+	struct mlxsw_sp_nexthop *nh;
+
+	list_splice_init(&old_rif->nexthop_list, &new_rif->nexthop_list);
+	list_for_each_entry(nh, &new_rif->nexthop_list, rif_list_node)
+		nh->rif = new_rif;
+	mlxsw_sp_nexthop_rif_update(mlxsw_sp, new_rif);
+}
+
 static void mlxsw_sp_nexthop_rif_gone_sync(struct mlxsw_sp *mlxsw_sp,
 					   struct mlxsw_sp_rif *rif)
 {