zebra: Remove possible NULL dereference in if_delete_connected

It is technically possible to attempt to use a NULL pointer.
Remove this from happening.

Additionally cleanup code indentation a small bit.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

diff --git a/zebra/interface.c b/zebra/interface.c
index dd1050ee7f066659b91e5ee2d52bada7ad6698af..18588ee52cfd2154f296d731f1ab36a4dffb3402 100644 (file)
--- a/zebra/interface.c
+++ b/zebra/interface.c
@@ -561,33 +561,35 @@ static void if_delete_connected(struct interface *ifp)
        struct prefix cp;
        struct route_node *rn;
        struct zebra_if *zebra_if;
+       struct listnode *node;
+       struct listnode *last = NULL;
 
        zebra_if = ifp->info;
 
-       if (ifp->connected) {
-               struct listnode *node;
-               struct listnode *last = NULL;
+       if (!ifp->connected)
+               return;
 
-               while ((node = (last ? last->next
-                                    : listhead(ifp->connected)))) {
-                       ifc = listgetdata(node);
+       while ((node = (last ? last->next
+                       : listhead(ifp->connected)))) {
+               ifc = listgetdata(node);
 
-                       cp = *CONNECTED_PREFIX(ifc);
-                       apply_mask(&cp);
+               cp = *CONNECTED_PREFIX(ifc);
+               apply_mask(&cp);
 
-                       if (cp.family == AF_INET
-                           && (rn = route_node_lookup(zebra_if->ipv4_subnets,
-                                                      &cp))) {
-                               struct listnode *anode;
-                               struct listnode *next;
-                               struct listnode *first;
-                               struct list *addr_list;
+               if (cp.family == AF_INET
+                   && (rn = route_node_lookup(zebra_if->ipv4_subnets,
+                                              &cp))) {
+                       struct listnode *anode;
+                       struct listnode *next;
+                       struct listnode *first;
+                       struct list *addr_list;
 
-                               route_unlock_node(rn);
-                               addr_list = (struct list *)rn->info;
+                       route_unlock_node(rn);
+                       addr_list = (struct list *)rn->info;
 
-                               /* Remove addresses, secondaries first. */
-                               first = listhead(addr_list);
+                       /* Remove addresses, secondaries first. */
+                       first = listhead(addr_list);
+                       if (first)
                                for (anode = first->next; anode || first;
                                     anode = next) {
                                        if (!anode) {
@@ -626,27 +628,26 @@ static void if_delete_connected(struct interface *ifp)
                                                last = node;
                                }
 
-                               /* Free chain list and respective route node. */
-                               list_delete_and_null(&addr_list);
-                               rn->info = NULL;
-                               route_unlock_node(rn);
-                       } else if (cp.family == AF_INET6) {
-                               connected_down(ifp, ifc);
+                       /* Free chain list and respective route node. */
+                       list_delete_and_null(&addr_list);
+                       rn->info = NULL;
+                       route_unlock_node(rn);
+               } else if (cp.family == AF_INET6) {
+                       connected_down(ifp, ifc);
 
-                               zebra_interface_address_delete_update(ifp, ifc);
+                       zebra_interface_address_delete_update(ifp, ifc);
 
-                               UNSET_FLAG(ifc->conf, ZEBRA_IFC_REAL);
-                               UNSET_FLAG(ifc->conf, ZEBRA_IFC_QUEUED);
+                       UNSET_FLAG(ifc->conf, ZEBRA_IFC_REAL);
+                       UNSET_FLAG(ifc->conf, ZEBRA_IFC_QUEUED);
 
-                               if (CHECK_FLAG(ifc->conf, ZEBRA_IFC_CONFIGURED))
-                                       last = node;
-                               else {
-                                       listnode_delete(ifp->connected, ifc);
-                                       connected_free(ifc);
-                               }
-                       } else {
+                       if (CHECK_FLAG(ifc->conf, ZEBRA_IFC_CONFIGURED))
                                last = node;
+                       else {
+                               listnode_delete(ifp->connected, ifc);
+                               connected_free(ifc);
                        }
+               } else {
+                       last = node;
                }
        }
 }