CID 348323: Memory - illegal accesses in lib/dns/zone.c

*** CID 348323:  Memory - illegal accesses  (UNINIT)
/lib/dns/zone.c: 23568 in setserial()
23562             if (newver != NULL) {
23563                     dns_db_closeversion(db, &newver, commit);
23564             }
23565             if (db != NULL) {
23566                     dns_db_detach(&db);
23567             }
>>>     CID 348323:  Memory - illegal accesses  (UNINIT)
>>>     Using uninitialized value "diff.tuples.head" when calling "dns_diff_clear".
23568             dns_diff_clear(&diff);
23569             isc_event_free(&event);
23570             dns_zone_idetach(&zone);
23571    
23572             INSIST(oldver == NULL);
23573             INSIST(newver == NULL);

The only code path in setserial() that can lead to calling dns_diff_clear(&diff); before initializing diff is when zone->update_disabled is true, here.

Fortunately, that exact condition is checked against just before calling setserial() here, so at this moment this bug should not be dangerous.