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https://github.com/isc-projects/bind9.git
synced 2026-06-10 16:59:59 -04:00
Fix data race on nta->expiry
Use CMM_LOAD_SHARED/CMM_STORE_SHARED for nta->expiry, which is written from the NTA's owning loop but read from any loop (validator, rndc status, rndc nta -dump). Also dispatch delete_expired to the NTA's owning loop rather than the caller's loop.
This commit is contained in:
Ondřej Surý
parent
fae6c6eead
commit
44bb3cd2a7
1 changed files with 35 additions and 31 deletions
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@ -147,6 +147,7 @@ fetch_done(void *arg) {
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isc_result_t eresult = resp->result;
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dns_ntatable_t *ntatable = nta->ntatable;
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isc_stdtime_t now = isc_stdtime_now();
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isc_stdtime_t expiry;
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rcu_read_lock();
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dns_view_t *view = rcu_dereference(ntatable->view);
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@ -167,14 +168,17 @@ fetch_done(void *arg) {
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dns_resolver_freefresp(&resp);
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expiry = CMM_LOAD_SHARED(nta->expiry);
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switch (eresult) {
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case ISC_R_SUCCESS:
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case DNS_R_NCACHENXDOMAIN:
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case DNS_R_NXDOMAIN:
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case DNS_R_NCACHENXRRSET:
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case DNS_R_NXRRSET:
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if (nta->expiry > now) {
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nta->expiry = now;
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if (expiry > now) {
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CMM_STORE_SHARED(nta->expiry, now);
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expiry = now;
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}
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break;
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default:
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@ -186,7 +190,7 @@ fetch_done(void *arg) {
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* as well stop the timer now.
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*/
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if (nta->timer != NULL &&
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(view == NULL || nta->expiry - now < view->nta_recheck))
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(view == NULL || expiry - now < view->nta_recheck))
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{
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isc_timer_stop(nta->timer);
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}
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@ -282,9 +286,8 @@ isc_result_t
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dns_ntatable_add(dns_ntatable_t *ntatable, const dns_name_t *name, bool force,
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isc_stdtime_t now, uint32_t lifetime) {
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isc_result_t result = ISC_R_SUCCESS;
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dns__nta_t *nta = NULL;
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dns__nta_t *nta = NULL, *old_nta = NULL;
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dns_qp_t *qp = NULL;
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void *pval = NULL;
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REQUIRE(VALID_NTATABLE(ntatable));
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@ -299,31 +302,28 @@ dns_ntatable_add(dns_ntatable_t *ntatable, const dns_name_t *name, bool force,
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dns_qpmulti_write(table, &qp);
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nta_create(ntatable, name, &nta);
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nta->forced = force;
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result = dns_qp_insert(qp, nta, 0);
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switch (result) {
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case ISC_R_EXISTS:
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result = dns_qp_getname(qp, &nta->name, DNS_DBNAMESPACE_NORMAL,
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&pval, NULL);
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if (result == ISC_R_SUCCESS) {
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/*
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* an NTA already existed: throw away the
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* new one and update the old one.
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*/
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dns__nta_detach(&nta); /* for nta_create */
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nta = pval;
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break;
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}
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/* update the NTA's timer as if it were new */
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result = dns_qp_deletename(qp, name, DNS_DBNAMESPACE_NORMAL,
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(void *)&old_nta, NULL);
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RUNTIME_CHECK(result == ISC_R_SUCCESS);
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dns__nta_shutdown(old_nta);
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dns__nta_detach(&old_nta);
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result = dns_qp_insert(qp, nta, 0);
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RUNTIME_CHECK(result == ISC_R_SUCCESS);
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FALLTHROUGH;
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case ISC_R_SUCCESS:
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nta->expiry = now + lifetime;
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CMM_STORE_SHARED(nta->expiry, now + lifetime);
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if (!force) {
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settimer(view, nta, lifetime);
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}
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break;
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default:
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break;
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UNREACHABLE();
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}
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dns_qp_compact(qp, DNS_QPGC_MAYBE);
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@ -388,7 +388,8 @@ delete_expired(void *arg) {
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result = dns_qp_getname(qp, &nta->name, DNS_DBNAMESPACE_NORMAL, &pval,
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NULL);
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if (result == ISC_R_SUCCESS &&
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((dns__nta_t *)pval)->expiry == nta->expiry)
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CMM_LOAD_SHARED(((dns__nta_t *)pval)->expiry) ==
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CMM_LOAD_SHARED(nta->expiry))
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{
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char nb[DNS_NAME_FORMATSIZE];
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dns_name_format(&nta->name, nb, sizeof(nb));
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@ -457,11 +458,11 @@ dns_ntatable_covered(dns_ntatable_t *ntatable, isc_stdtime_t now,
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goto done;
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}
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if (nta->expiry <= now) {
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if (CMM_LOAD_SHARED(nta->expiry) <= now) {
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/* NTA is expired */
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dns__nta_ref(nta);
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dns_ntatable_ref(nta->ntatable);
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isc_async_current(delete_expired, nta);
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isc_async_run(nta->loop, delete_expired, nta);
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goto done;
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}
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@ -510,19 +511,20 @@ dns_ntatable_totext(dns_ntatable_t *ntatable, const char *view,
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char obuf[DNS_NAME_FORMATSIZE + ISC_FORMATHTTPTIMESTAMP_SIZE +
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sizeof("expired: \n")];
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isc_time_t t;
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isc_stdtime_t expiry = CMM_LOAD_SHARED(n->expiry);
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dns_name_format(&n->name, nbuf, sizeof(nbuf));
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if (n->expiry != 0xffffffffU) {
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if (expiry != 0xffffffffU) {
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/* Normal NTA entries */
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isc_time_set(&t, n->expiry, 0);
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isc_time_set(&t, expiry, 0);
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isc_time_formattimestamp(&t, tbuf, sizeof(tbuf));
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snprintf(obuf, sizeof(obuf), "%s%s%s%s: %s %s",
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first ? "" : "\n", nbuf,
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view != NULL ? "/" : "",
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view != NULL ? view : "",
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n->expiry <= now ? "expired" : "expiry", tbuf);
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expiry <= now ? "expired" : "expiry", tbuf);
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} else {
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/* "validate-except" entries */
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snprintf(obuf, sizeof(obuf), "%s%s%s%s: %s",
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@ -566,12 +568,13 @@ dns_ntatable_save(dns_ntatable_t *ntatable, FILE *fp) {
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dns__nta_t *n = pval;
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isc_buffer_t b;
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char nbuf[DNS_NAME_FORMATSIZE + 1], tbuf[80];
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isc_stdtime_t expiry = CMM_LOAD_SHARED(n->expiry);
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/*
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* Skip this node if the expiry is already in the
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* past, or if this is a "validate-except" entry.
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*/
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if (n->expiry <= now || n->expiry == 0xffffffffU) {
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if (expiry <= now || expiry == 0xffffffffU) {
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continue;
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}
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@ -585,7 +588,7 @@ dns_ntatable_save(dns_ntatable_t *ntatable, FILE *fp) {
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isc_buffer_putuint8(&b, 0);
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isc_buffer_init(&b, tbuf, sizeof(tbuf));
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dns_time32_totext(n->expiry, &b);
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dns_time32_totext(expiry, &b);
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/* Zero terminate */
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isc_buffer_putuint8(&b, 0);
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@ -651,9 +654,10 @@ dns_ntatable_shutdown(dns_ntatable_t *ntatable) {
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dns_qpiter_init(&qpr, &iter);
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while (dns_qpiter_next(&iter, &pval, NULL) == ISC_R_SUCCESS) {
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dns__nta_t *n = pval;
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dns__nta_shutdown(n);
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dns__nta_detach(&n);
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dns__nta_t *nta = pval;
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dns__nta_shutdown(nta);
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dns__nta_detach(&nta);
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}
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dns_qpread_destroy(table, &qpr);
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