netdev: check for NULL fields in netdev_get_addrs

When the interfaces list is retrieved through getiffaddrs(), there
might be elements with iface_name set to NULL.

This patch checks ifa_name to be not NULL before comparing it to the
actual device name in the loop that calculates how many interfaces
exist with that same name.

Also, this patch checks that ifa_netmask is not NULL for coherence
with the existing code so that it doesn't allocate more memory
than needed if this field is NULL.

Note, that these checks are already being done later in the function
so it should be done in both places.

Signed-off-by: Daniel Alvarez <dalvarez@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Lance Richardson <lrichard@redhat.com>

lib/netdev.c

@@ -1890,7 +1890,7 @@ netdev_get_addrs(const char dev[], struct in6_addr **paddr,
     }
 
     for (ifa = if_addr_list; ifa; ifa = ifa->ifa_next) {
-        if (ifa->ifa_addr != NULL) {
+        if (ifa->ifa_addr && ifa->ifa_name && ifa->ifa_netmask) {
             int family;
 
             family = ifa->ifa_addr->sa_family;