From: Ondřej Surý <ondrej@isc.org>
Date: Thu, 19 Mar 2026 02:42:08 +0000 (+0100)
Subject: Fix data race on fctx->vresult in validated()
X-Git-Tag: v9.21.21~24^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a2bd8339095c99b4f0faea0f1bc39128c048c3aa;p=thirdparty%2Fbind9.git

Fix data race on fctx->vresult in validated()

Move the write to fctx->vresult after LOCK(&fctx->lock).  The field was
being set before acquiring the lock, but dns_resolver_logfetch() reads
it under the same lock from another thread.
---

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index a708bd0f0b1..bf800ff067e 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -5626,7 +5626,6 @@ validated(void *arg) {
 	addrinfo = valarg->addrinfo;
 
 	message = val->message;
-	fctx->vresult = val->result;
 
 	FCTXTRACE("received validation completion event");
 
@@ -5634,6 +5633,8 @@ validated(void *arg) {
 
 	LOCK(&fctx->lock);
 
+	fctx->vresult = val->result;
+
 	ISC_LIST_UNLINK(fctx->validators, val, link);
 
 	if (SHUTTINGDOWN(fctx)) {