ofproto-dpif-upcall: Fix action attr iteration.

This calls is operating on messages generated by the datapath. If a
datapath implementation sends improperly formatted netlink attributes,
then it's possible for a revalidator thread to end up trapped in an
infinite loop iterating across the actions attributes. Rather than using
the UNSAFE variation of this iterator, use the regular version.

Fixes: e672ff9 ("ofproto-dpif: Restore metadata and registers on recirculation.")
Signed-off-by: Joe Stringer <[email protected]>
Acked-by: Ben Pfaff <[email protected]>

ofproto/ofproto-dpif-upcall.c

@@ -1655,7 +1655,7 @@ ukey_create_from_dpif_flow(const struct udpif *udpif,
             return EINVAL;
         }
     }
-    NL_ATTR_FOR_EACH_UNSAFE (a, left, flow->actions, flow->actions_len) {
+    NL_ATTR_FOR_EACH (a, left, flow->actions, flow->actions_len) {
         if (nl_attr_type(a) == OVS_ACTION_ATTR_RECIRC) {
             return EINVAL;
         }