From e1c4e29b1b4fca20743df44796d61adcaa399ca2 Mon Sep 17 00:00:00 2001
From: Tony Finch <fanf@isc.org>
Date: Tue, 28 Feb 2023 12:57:29 +0000
Subject: [PATCH] Revert !7538, simplify locking in dns_view_detach()

This reverts commit eb6b31b6, which led to a null pointer dereference
in adb when the resolver tried to use it after it was detached.

Closes #3898
---
 lib/dns/view.c | 38 +++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/lib/dns/view.c b/lib/dns/view.c
index 0cf2a4802e..d26e9d0e37 100644
--- a/lib/dns/view.c
+++ b/lib/dns/view.c
@@ -518,15 +518,36 @@ dns_view_detach(dns_view_t **viewp) {
 		if (view->resolver != NULL) {
 			resolver = view->resolver;
 			view->resolver = NULL;
+			UNLOCK(&view->lock);
+
+			dns_resolver_shutdown(resolver);
+			dns_resolver_detach(&resolver);
+
+			LOCK(&view->lock);
 		}
+
 		if (view->adb != NULL) {
 			adb = view->adb;
 			view->adb = NULL;
+			UNLOCK(&view->lock);
+
+			dns_adb_shutdown(adb);
+			dns_adb_detach(&adb);
+
+			LOCK(&view->lock);
 		}
+
 		if (view->requestmgr != NULL) {
 			requestmgr = view->requestmgr;
 			view->requestmgr = NULL;
+			UNLOCK(&view->lock);
+
+			dns_requestmgr_shutdown(requestmgr);
+			dns_requestmgr_detach(&requestmgr);
+
+			LOCK(&view->lock);
 		}
+
 		if (view->zonetable != NULL) {
 			zt = view->zonetable;
 			view->zonetable = NULL;
@@ -534,6 +555,7 @@ dns_view_detach(dns_view_t **viewp) {
 				dns_zt_flush(zt);
 			}
 		}
+
 		if (view->managed_keys != NULL) {
 			mkzone = view->managed_keys;
 			view->managed_keys = NULL;
@@ -557,25 +579,15 @@ dns_view_detach(dns_view_t **viewp) {
 		}
 		UNLOCK(&view->lock);
 
-		/* Detach outside view lock */
-		if (resolver != NULL) {
-			dns_resolver_shutdown(resolver);
-			dns_resolver_detach(&resolver);
-		}
-		if (adb != NULL) {
-			dns_adb_shutdown(adb);
-			dns_adb_detach(&adb);
-		}
-		if (requestmgr != NULL) {
-			dns_requestmgr_shutdown(requestmgr);
-			dns_requestmgr_detach(&requestmgr);
-		}
+		/* Need to detach zt and zones outside view lock */
 		if (zt != NULL) {
 			dns_zt_detach(&zt);
 		}
+
 		if (mkzone != NULL) {
 			dns_zone_detach(&mkzone);
 		}
+
 		if (rdzone != NULL) {
 			dns_zone_detach(&rdzone);
 		}