From b4f3fafcffad55e64ec8958691db41a417320bb0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Witold=20Kr=C4=99cicki?= Date: Thu, 21 May 2020 11:18:53 +0200 Subject: [PATCH] Fix assertion failure during startup when the server is under load. When we're coming back from recursion fetch_callback does not accept DNS_R_NXDOMAIN as an rcode - query_gotanswer calls query_nxdomain in which an assertion fails on qctx->is_zone. Yet, under some circumstances, qname minimization will return an DNS_R_NXDOMAIN - when root zone mirror is not yet loaded. The fix changes the DNS_R_NXDOMAIN answer to DNS_R_SERVFAIL. --- lib/dns/resolver.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c index 5a1f0c9f06..8aa78191e8 100644 --- a/lib/dns/resolver.c +++ b/lib/dns/resolver.c @@ -4397,6 +4397,15 @@ resume_qmin(isc_task_t *task, isc_event_t *event) { fctx->now, findoptions, true, true, &fctx->nameservers, NULL); + /* + * DNS_R_NXDOMAIN here means we have not loaded the root zone mirror + * yet - but DNS_R_NXDOMAIN is not a valid return value when doing + * recursion, we need to patch it. + */ + if (result == DNS_R_NXDOMAIN) { + result = DNS_R_SERVFAIL; + } + if (result != ISC_R_SUCCESS) { fctx_done(fctx, result, __LINE__); goto cleanup;