- Fix that fast_reload when a zonemd verification lookup

it in progress with subnet loaded, deregisters the
  callback. Thanks to Qifan Zhang, Palo Alto Networks,
  for the report.

daemon/remote.c

@@ -7612,7 +7612,8 @@ auth_zone_zonemd_stop_lookup(struct auth_zone* z, struct mesh_area* mesh)
 	qinfo.local_alias = NULL;
 
 	mesh_remove_callback(mesh, &qinfo, qflags,
-		&auth_zonemd_dnskey_lookup_callback, z);
+		&auth_zonemd_dnskey_lookup_callback, z,
+		z->zonemd_callback_unique_info);
 }
 
 /** Pick up the auth zone locks. */

doc/Changelog

@@ -17,6 +17,10 @@
 	- Fix that misconfigured `iter-scrub-ns: 0` causes request
 	  failures. Thanks to Qifan Zhang, Palo Alto Networks,
 	  for the report.
+	- Fix that fast_reload when a zonemd verification lookup
+	  it in progress with subnet loaded, deregisters the
+	  callback. Thanks to Qifan Zhang, Palo Alto Networks,
+	  for the report.
 
 12 June 2026: Wouter
 	- Fix that for auth-zone and rpz zones the allow-notify

libunbound/context.h

@@ -167,6 +167,8 @@ struct ctx_query {
         ub_event_callback_type cb_event;
 	/** for async query, the callback user arg */
 	void* cb_arg;
+	/** for async query the unique info */
+	void* unique_info;
 
 	/** answer message, result from resolver lookup. */
 	uint8_t* msg;

libunbound/libworker.c

@@ -642,7 +642,8 @@ int libworker_fg(struct ub_ctx* ctx, struct ctx_query* q)
 	}
 	/* process new query */
 	if(!mesh_new_callback(w->env->mesh, &qinfo, qflags, &edns, 
-		w->back->udp_buff, qid, libworker_fg_done_cb, q, 0)) {
+		w->back->udp_buff, qid, libworker_fg_done_cb, q, 0,
+		&q->unique_info)) {
 		free(qinfo.qname);
 		return UB_NOMEM;
 	}
@@ -723,7 +724,8 @@ int libworker_attach_mesh(struct ub_ctx* ctx, struct ctx_query* q,
 	if(async_id)
 		*async_id = q->querynum;
 	if(!mesh_new_callback(w->env->mesh, &qinfo, qflags, &edns, 
-		w->back->udp_buff, qid, libworker_event_done_cb, q, 0)) {
+		w->back->udp_buff, qid, libworker_event_done_cb, q, 0,
+		&q->unique_info)) {
 		free(qinfo.qname);
 		return UB_NOMEM;
 	}
@@ -861,7 +863,8 @@ handle_newq(struct libworker* w, uint8_t* buf, uint32_t len)
 	q->w = w;
 	/* process new query */
 	if(!mesh_new_callback(w->env->mesh, &qinfo, qflags, &edns, 
-		w->back->udp_buff, qid, libworker_bg_done_cb, q, 0)) {
+		w->back->udp_buff, qid, libworker_bg_done_cb, q, 0,
+		&q->unique_info)) {
 		add_bg_result(w, q, NULL, UB_NOMEM, NULL, 0);
 	}
 	free(qinfo.qname);

services/authzone.c

@@ -5558,7 +5558,8 @@ xfr_transfer_lookup_host(struct auth_xfer* xfr, struct module_env* env)
 	 * called straight away */
 	lock_basic_unlock(&xfr->lock);
 	if(!mesh_new_callback(env->mesh, &qinfo, qflags, &edns, buf, 0,
-		&auth_xfer_transfer_lookup_callback, xfr, 0)) {
+		&auth_xfer_transfer_lookup_callback, xfr, 0,
+		&xfr->task_transfer->lookup_unique_info)) {
 		lock_basic_lock(&xfr->lock);
 		log_err("out of memory lookup up master %s", master->host);
 		return 0;
@@ -6804,7 +6805,8 @@ xfr_probe_lookup_host(struct auth_xfer* xfr, struct module_env* env)
 	 * called straight away */
 	lock_basic_unlock(&xfr->lock);
 	if(!mesh_new_callback(env->mesh, &qinfo, qflags, &edns, buf, 0,
-		&auth_xfer_probe_lookup_callback, xfr, 0)) {
+		&auth_xfer_probe_lookup_callback, xfr, 0,
+		&xfr->task_probe->lookup_unique_info)) {
 		lock_basic_lock(&xfr->lock);
 		log_err("out of memory lookup up master %s", master->host);
 		return 0;
@@ -8640,7 +8642,8 @@ zonemd_lookup_dnskey(struct auth_zone* z, struct module_env* env)
 	/* the callback can be called straight away */
 	lock_rw_unlock(&z->lock);
 	if(!mesh_new_callback(env->mesh, &qinfo, qflags, &edns, buf, 0,
-		&auth_zonemd_dnskey_lookup_callback, z, 0)) {
+		&auth_zonemd_dnskey_lookup_callback, z, 0,
+		&z->zonemd_callback_unique_info)) {
 		lock_rw_wrlock(&z->lock);
 		log_err("out of memory lookup of %s for zonemd",
 			(fetch_ds?"DS":"DNSKEY"));

services/authzone.h

@@ -144,6 +144,8 @@ struct auth_zone {
 	struct module_env* zonemd_callback_env;
 	/** for the zonemd callback, the type of data looked up */
 	uint16_t zonemd_callback_qtype;
+	/** for the zonemd callback, the unique info */
+	void* zonemd_callback_unique_info;
 	/** zone has been deleted */
 	int zone_deleted;
 	/** deletelist pointer, unused normally except during delete */
@@ -344,6 +346,8 @@ struct auth_probe {
 
 	/** for the hostname lookups, which master is current */
 	struct auth_master* lookup_target;
+	/** for the lookup, the callback unique info */
+	void* lookup_unique_info;
 	/** are we looking up A or AAAA, first A, then AAAA (if ip6 enabled) */
 	int lookup_aaaa;
 	/** we only want to do lookups for making config work (for notify),
@@ -402,6 +406,8 @@ struct auth_transfer {
 
 	/** for the hostname lookups, which master is current */
 	struct auth_master* lookup_target;
+	/** for the lookup, the callback unique info */
+	void* lookup_unique_info;
 	/** are we looking up A or AAAA, first A, then AAAA (if ip6 enabled) */
 	int lookup_aaaa;
 

services/mesh.c

@@ -662,7 +662,8 @@ servfail_mem:
 int
 mesh_new_callback(struct mesh_area* mesh, struct query_info* qinfo,
 	uint16_t qflags, struct edns_data* edns, sldns_buffer* buf,
-	uint16_t qid, mesh_cb_func_type cb, void* cb_arg, int rpz_passthru)
+	uint16_t qid, mesh_cb_func_type cb, void* cb_arg, int rpz_passthru,
+	void** unique_info)
 {
 	struct mesh_state* s = NULL;
 	int unique = unique_mesh_state(edns->opt_list_in, mesh->env);
@@ -751,6 +752,8 @@ mesh_new_callback(struct mesh_area* mesh, struct query_info* qinfo,
 		mesh->num_reply_states ++;
 	}
 	mesh->num_reply_addrs++;
+	if(unique_info)
+		*unique_info = s->unique;
 	if(added)
 		mesh_run(mesh, s, module_event_new, NULL);
 	return 1;
@@ -1969,6 +1972,25 @@ struct mesh_state* mesh_area_find(struct mesh_area* mesh,
 	return result;
 }
 
+struct mesh_state* mesh_area_find_unique(struct mesh_area* mesh,
+	struct respip_client_info* cinfo, struct query_info* qinfo,
+	uint16_t qflags, int prime, int valrec, void* unique_info)
+{
+	struct mesh_state key;
+	struct mesh_state* result;
+
+	key.node.key = &key;
+	key.s.is_priming = prime;
+	key.s.is_valrec = valrec;
+	key.s.qinfo = *qinfo;
+	key.s.query_flags = qflags;
+	key.unique = (struct mesh_state*)unique_info;
+	key.s.client_info = cinfo;
+
+	result = (struct mesh_state*)rbtree_search(&mesh->all, &key);
+	return result;
+}
+
 /** remove mesh state callback */
 int mesh_state_del_cb(struct mesh_state* s, mesh_cb_func_type cb, void* cb_arg)
 {
@@ -2700,13 +2722,30 @@ int mesh_jostle_exceeded(struct mesh_area* mesh)
 }
 
 void mesh_remove_callback(struct mesh_area* mesh, struct query_info* qinfo,
-	uint16_t qflags, mesh_cb_func_type cb, void* cb_arg)
+	uint16_t qflags, mesh_cb_func_type cb, void* cb_arg, void* unique_info)
 {
 	struct mesh_state* s = NULL;
 	s = mesh_area_find(mesh, NULL, qinfo, qflags&(BIT_RD|BIT_CD), 0, 0);
-	if(!s) return;
-	if(!mesh_state_del_cb(s, cb, cb_arg)) return;
+	if(s && mesh_state_del_cb(s, cb, cb_arg))
+		goto removed;
+	if(unique_info) {
+		s = mesh_area_find_unique(mesh, NULL, qinfo,
+			qflags&(BIT_RD|BIT_CD), 0, 0, unique_info);
+		if(s && mesh_state_del_cb(s, cb, cb_arg))
+			goto removed;
+	}
+	/* mesh_area_find builds key.unique=NULL and cannot match a state
+	 * created with mesh_state_make_unique (e.g. subnetcache sets
+	 * env->unique_mesh). Fall back to a linear scan; cb+cb_arg is an
+	 * exact key (mesh_state_del_cb compares both).
+	 * This works for both lookups for zonemd and for hostname authzone. */
+	RBTREE_FOR(s, struct mesh_state*, &mesh->all) {
+		if(s->cb_list && mesh_state_del_cb(s, cb, cb_arg))
+			goto removed;
+	}
+	return;
 
+removed:
 	/* It was in the list and removed. */
 	log_assert(mesh->num_reply_addrs > 0);
 	mesh->num_reply_addrs--;

services/mesh.h

@@ -342,11 +342,14 @@ void mesh_new_client(struct mesh_area* mesh, struct query_info* qinfo,
  * @param cb_arg: callback user arg.
  * @param rpz_passthru: if true, the rpz passthru was previously found and
  * 	further rpz processing is stopped.
+ * @param unique_info: if nonnull, unique info is passed back to be used
+ *	for the callback remove call. It does not need to be deallocated.
  * @return 0 on error.
  */
 int mesh_new_callback(struct mesh_area* mesh, struct query_info* qinfo,
 	uint16_t qflags, struct edns_data* edns, struct sldns_buffer* buf, 
-	uint16_t qid, mesh_cb_func_type cb, void* cb_arg, int rpz_passthru);
+	uint16_t qid, mesh_cb_func_type cb, void* cb_arg, int rpz_passthru,
+	void** unique_info);
 
 /**
  * New prefetch message. Create new query state if needed.
@@ -543,6 +546,23 @@ struct mesh_state* mesh_area_find(struct mesh_area* mesh,
 	struct respip_client_info* cinfo, struct query_info* qinfo,
 	uint16_t qflags, int prime, int valrec);
 
+/**
+ * Find a unique mesh state in the mesh area. Pass relevant flags.
+ *
+ * @param mesh: the mesh area to look in.
+ * @param cinfo: if non-NULL client specific info that may affect IP-based
+ * 	actions that apply to the query result.
+ * @param qinfo: what query
+ * @param qflags: if RD / CD bit is set or not.
+ * @param prime: if it is a priming query.
+ * @param valrec: if it is a validation-recursion query.
+ * @param unique_info: the unique info for the state. NULL can be passed.
+ * @return: mesh state or NULL if not found.
+ */
+struct mesh_state* mesh_area_find_unique(struct mesh_area* mesh,
+	struct respip_client_info* cinfo, struct query_info* qinfo,
+	uint16_t qflags, int prime, int valrec, void* unique_info);
+
 /**
  * Setup attachment super/sub relation between super and sub mesh state.
  * The relation must not be present when calling the function.
@@ -736,8 +756,9 @@ void mesh_respond_serve_expired(struct mesh_state* mstate);
  * @param qflags: flags from client query.
  * @param cb: callback function.
  * @param cb_arg: callback user arg.
+ * @param unique_info: if not NULL, used to find a unique state for removal.
  */
 void mesh_remove_callback(struct mesh_area* mesh, struct query_info* qinfo,
-	uint16_t qflags, mesh_cb_func_type cb, void* cb_arg);
+	uint16_t qflags, mesh_cb_func_type cb, void* cb_arg, void* unique_info);
 
 #endif /* SERVICES_MESH_H */

validator/autotrust.c

@@ -2431,7 +2431,7 @@ probe_anchor(struct module_env* env, struct trust_anchor* tp)
 		qinfo.qclass);
 
 	if(!mesh_new_callback(env->mesh, &qinfo, qflags, &edns, buf, 0, 
-		&probe_answer_cb, env, 0)) {
+		&probe_answer_cb, env, 0, NULL)) {
 		log_err("out of memory making 5011 probe");
 	}
 }