upstream/bind9
1
0
Fork 0
mirror of https://github.com/isc-projects/bind9.git synced 2026-05-23 10:37:43 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions 4

Fix cache flush ordering on NTA expiry

Browse source 
dns_view_flushnode() was called in the delete_expired() async
callback, which runs after the query that detected the NTA expiry.
This created a race: the query would proceed with stale cached data
from the NTA period before the flush had a chance to run, resulting
in transient SERVFAIL with EDE 22 (No Reachable Authority).

Move dns_view_flushnode() into dns_ntatable_covered() so the cache
is flushed synchronously when the expiry is detected, before the
query continues.

Also simplify the expiry comparison in delete_expired() to a direct
pointer comparison (nta == pval) instead of comparing expiry
timestamps.
This commit is contained in:
Ondřej Surý 2026-03-20 14:29:57 +01:00
parent 892f50712d
commit da8e1c956a
No known key found for this signature in database
GPG key ID: 2820F37E873DEA41
1 changed files with 11 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
lib/dns/nta.c
View file

@ -373,7 +373,6 @@ delete_expired(void *arg) {
isc_result_t result;
dns_qp_t *qp = NULL;
void *pval = NULL;
bool flushnode = false;
REQUIRE(VALID_NTATABLE(ntatable));
@ -387,17 +386,12 @@ delete_expired(void *arg) {
dns_qpmulti_write(table, &qp);
result = dns_qp_getname(qp, &nta->name, DNS_DBNAMESPACE_NORMAL, &pval,
NULL);
if (result == ISC_R_SUCCESS &&
CMM_LOAD_SHARED(((dns__nta_t *)pval)->expiry) ==
CMM_LOAD_SHARED(nta->expiry))
{
if (result == ISC_R_SUCCESS && nta == pval) {
char nb[DNS_NAME_FORMATSIZE];
dns_name_format(&nta->name, nb, sizeof(nb));
isc_log_write(DNS_LOGCATEGORY_DNSSEC, DNS_LOGMODULE_NTA,
ISC_LOG_INFO, "deleting expired NTA at %s", nb);
flushnode = true;
result = dns_qp_deletename(qp, &nta->name,
DNS_DBNAMESPACE_NORMAL, NULL, NULL);
RUNTIME_CHECK(result == ISC_R_SUCCESS);
@ -406,9 +400,6 @@ delete_expired(void *arg) {
}
dns_qp_compact(qp, DNS_QPGC_MAYBE);
dns_qpmulti_commit(table, &qp);
if (flushnode) {
dns_view_flushnode(view, &nta->name, true);
}
unlock:
rcu_read_unlock();
dns__nta_detach(&nta);
@ -423,15 +414,16 @@ dns_ntatable_covered(dns_ntatable_t *ntatable, isc_stdtime_t now,
bool answer = false;
dns_qpread_t qpr;
void *pval = NULL;
bool flushnode = false;
REQUIRE(VALID_NTATABLE(ntatable));
REQUIRE(dns_name_isabsolute(name));
rcu_read_lock();
dns_view_t *view = rcu_dereference(ntatable->view);
dns_qpmulti_t *table = rcu_dereference(ntatable->table);
if (table == NULL) {
rcu_read_unlock();
return false;
if (view == NULL || table == NULL) {
goto unlock;
}
dns_qpmulti_query(table, &qpr);
@ -462,6 +454,7 @@ dns_ntatable_covered(dns_ntatable_t *ntatable, isc_stdtime_t now,
/* NTA is expired */
dns__nta_ref(nta);
dns_ntatable_ref(nta->ntatable);
flushnode = true;
isc_async_run(nta->loop, delete_expired, nta);
goto done;
}
@ -469,6 +462,11 @@ dns_ntatable_covered(dns_ntatable_t *ntatable, isc_stdtime_t now,
answer = true;
done:
dns_qpread_destroy(table, &qpr);
if (nta != NULL && flushnode) {
dns_view_flushnode(view, &nta->name, true);
}
unlock:
rcu_read_unlock();
return answer;