From: Mark Andrews <marka@isc.org>
Date: Thu, 28 Nov 2019 22:59:03 +0000 (+1100)
Subject: Assign fctx->client when fctx is created rather when the join happens.
X-Git-Tag: v9.15.7~45^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9ca6ad6311f3305cfefab32187c22afe48be30be;p=thirdparty%2Fbind9.git

Assign fctx->client when fctx is created rather when the join happens.

This prevents races on fctx->client whenever a new fetch joins a existing
fetch (by calling fctx_join) as it is now invariant for the active life of
fctx.
---

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 9fba6ca6630..9b89c0aa5a4 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -359,8 +359,8 @@ struct fetchctx {
 	/*%
 	 * Random numbers to use for mixing up server addresses.
 	 */
-	uint32_t                    rand_buf;
-	uint32_t                    rand_bits;
+	uint32_t                    	rand_buf;
+	uint32_t                    	rand_bits;
 
 	/*%
 	 * Fetch-local statistics for detailed logging.
@@ -370,7 +370,7 @@ struct fetchctx {
 	int				exitline;
 	isc_time_t			start;
 	uint64_t			duration;
-	bool			logged;
+	bool				logged;
 	unsigned int			querysent;
 	unsigned int			referrals;
 	unsigned int			lamecount;
@@ -380,7 +380,7 @@ struct fetchctx {
 	unsigned int			adberr;
 	unsigned int			findfail;
 	unsigned int			valfail;
-	bool			timeout;
+	bool				timeout;
 	dns_adbaddrinfo_t 		*addrinfo;
 	const isc_sockaddr_t		*client;
 	dns_messageid_t			id;
@@ -4692,8 +4692,6 @@ fctx_join(fetchctx_t *fctx, isc_task_t *task, const isc_sockaddr_t *client,
 
 	fctx_increference(fctx);
 
-	fctx->client = client;
-
 	fetch->magic = DNS_FETCH_MAGIC;
 	fetch->private = fctx;
 
@@ -4717,8 +4715,9 @@ log_ns_ttl(fetchctx_t *fctx, const char *where) {
 static isc_result_t
 fctx_create(dns_resolver_t *res, const dns_name_t *name, dns_rdatatype_t type,
 	    const dns_name_t *domain, dns_rdataset_t *nameservers,
-	    unsigned int options, unsigned int bucketnum, unsigned int depth,
-	    isc_counter_t *qc, fetchctx_t **fctxp)
+	    const isc_sockaddr_t *client, unsigned int options,
+	    unsigned int bucketnum, unsigned int depth, isc_counter_t *qc,
+	    fetchctx_t **fctxp)
 {
 	fetchctx_t *fctx;
 	isc_result_t result;
@@ -4830,7 +4829,7 @@ fctx_create(dns_resolver_t *res, const dns_name_t *name, dns_rdatatype_t type,
 	fctx->rand_bits = 0;
 	fctx->timeout = false;
 	fctx->addrinfo = NULL;
-	fctx->client = NULL;
+	fctx->client = client;
 	fctx->ns_ttl = 0;
 	fctx->ns_ttl_ok = false;
 
@@ -10569,7 +10568,8 @@ dns_resolver_createfetch(dns_resolver_t *res, const dns_name_t *name,
 
 	if (fctx == NULL) {
 		result = fctx_create(res, name, type, domain, nameservers,
-				     options, bucketnum, depth, qc, &fctx);
+				     client, options, bucketnum, depth, qc,
+				     &fctx);
 		if (result != ISC_R_SUCCESS)
 			goto unlock;
 		new_fctx = true;