virDomainNumaGetNodeDistance: Fix input arguments validation

There's no point in checking if numa->mem_nodes[node].ndistances
is set if we check for numa->mem_nodes[node].distances. However,
it makes sense to check if the sibling node (@cellid) caller
passed falls within boundaries.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/conf/numa_conf.c

@@ -1153,8 +1153,8 @@ virDomainNumaGetNodeDistance(virDomainNumaPtr numa,
      * defined default for local and remote nodes.
      */
     if (!distances ||
-        !distances[cellid].value ||
-        !numa->mem_nodes[node].ndistances)
+        cellid >= numa->nmem_nodes ||
+        !distances[cellid].value)
         return (node == cellid) ? LOCAL_DISTANCE : REMOTE_DISTANCE;
 
     return distances[cellid].value;