conf: fix query_modules list reuse upon conf-commit (adding zones)

src/knot/common/stats.c

@@ -168,7 +168,7 @@ static void dump_to_file(FILE *fd, server_t *server)
 
 	dump_ctx_t ctx = {
 		.fd = fd,
-		.query_modules = &conf()->query_modules,
+		.query_modules = conf()->query_modules,
 	};
 
 	// Dump global statistics.

src/knot/conf/base.c

@@ -157,9 +157,6 @@ int conf_new(
 	}
 	memset(out, 0, sizeof(conf_t));
 
-	// Initialize query modules list.
-	init_list(&out->query_modules);
-
 	// Initialize config schema.
 	int ret = yp_schema_copy(&out->schema, schema);
 	if (ret != KNOT_EOK) {
@@ -174,6 +171,14 @@ int conf_new(
 	}
 	mm_ctx_mempool(out->mm, MM_DEFAULT_BLKSIZE);
 
+	// Initialize query modules list.
+	out->query_modules = mm_alloc(out->mm, sizeof(list_t));
+	if (out->query_modules == NULL) {
+		ret = KNOT_ENOMEM;
+		goto new_error;
+	}
+	init_list(out->query_modules);
+
 	// Set the DB api.
 	out->api = knot_db_lmdb_api();
 	struct knot_db_lmdb_opts lmdb_opts = KNOT_DB_LMDB_OPTS_INITIALIZER;
@@ -290,9 +295,19 @@ int conf_clone(
 	out->mm = s_conf->mm;
 	out->db = s_conf->db;
 
+	// Initialize query modules list.
+	out->query_modules = mm_alloc(out->mm, sizeof(list_t));
+	if (out->query_modules == NULL) {
+		yp_schema_free(out->schema);
+		free(out);
+		return KNOT_ENOMEM;
+	}
+	init_list(out->query_modules);
+
 	// Open common read-only transaction.
 	ret = conf_refresh_txn(out);
 	if (ret != KNOT_EOK) {
+		mm_free(out->mm, out->query_modules);
 		yp_schema_free(out->schema);
 		free(out);
 		return ret;
@@ -308,9 +323,6 @@ int conf_clone(
 		out->hostname = strdup(s_conf->hostname);
 	}
 
-	// Initialize query modules list.
-	init_list(&out->query_modules);
-
 	// Initialize cached values.
 	init_cache(out);
 
@@ -334,8 +346,7 @@ conf_t *conf_update(
 			conf->io.zones = s_conf->io.zones;
 		}
 		if ((flags & CONF_UPD_FMODULES) && s_conf != NULL) {
-			list_dup(&conf->query_modules, &s_conf->query_modules,
-			         sizeof(knotd_mod_t));
+			conf->query_modules = s_conf->query_modules;
 			conf->query_plan = s_conf->query_plan;
 		}
 	}
@@ -353,7 +364,7 @@ conf_t *conf_update(
 			old_conf->io.zones = NULL;
 		}
 		if (flags & CONF_UPD_FMODULES) {
-			WALK_LIST_FREE(old_conf->query_modules);
+			old_conf->query_modules = NULL;
 			old_conf->query_plan = NULL;
 		}
 		if (!(flags & CONF_UPD_FNOFREE)) {
@@ -388,7 +399,8 @@ void conf_free(
 	}
 
 	conf_mod_load_purge(conf, false);
-	conf_deactivate_modules(&conf->query_modules, &conf->query_plan);
+	conf_deactivate_modules(conf->query_modules, &conf->query_plan);
+	mm_free(conf->mm, conf->query_modules);
 	conf_mod_unload_shared(conf);
 
 	if (!conf->is_clone) {

src/knot/conf/base.h

@@ -132,7 +132,7 @@ typedef struct {
 	/*! List of old schemas (lazy freed). */
 	old_schema_dynarray_t old_schemas;
 	/*! List of active query modules. */
-	list_t query_modules;
+	list_t *query_modules;
 	/*! Default query modules plan. */
 	struct query_plan *query_plan;
 } conf_t;

src/knot/ctl/commands.c

@@ -1328,7 +1328,7 @@ static int ctl_stats(ctl_args_t *args, ctl_cmd_t cmd)
 
 	// Process modules metrics.
 	if (section == NULL || strncasecmp(section, "mod-", strlen("mod-")) == 0) {
-		int ret = modules_stats(&conf()->query_modules, args, NULL);
+		int ret = modules_stats(conf()->query_modules, args, NULL);
 		if (ret != KNOT_EOK) {
 			send_error(args, knot_strerror(ret));
 			return ret;

src/knot/server/server.c

@@ -657,7 +657,7 @@ int server_reload(server_t *server)
 			return ret;
 		}
 
-		conf_activate_modules(new_conf, NULL, &new_conf->query_modules,
+		conf_activate_modules(new_conf, NULL, new_conf->query_modules,
 		                      &new_conf->query_plan);
 	}
 

src/utils/knotd/main.c

@@ -368,7 +368,7 @@ static int set_config(const char *confdb, const char *config)
 	}
 
 	/* Activate global query modules. */
-	conf_activate_modules(new_conf, NULL, &new_conf->query_modules,
+	conf_activate_modules(new_conf, NULL, new_conf->query_modules,
 	                      &new_conf->query_plan);
 
 	/* Update to the new config. */

tests-extra/tests/ctl/basic/test.py

@@ -5,6 +5,7 @@
 import os
 
 from dnstest.libknot import libknot
+from dnstest.module import ModStats
 from dnstest.test import Test
 from dnstest.utils import *
 
@@ -12,6 +13,9 @@ t = Test()
 
 knot = t.server("knot")
 
+# Enable a global module to check the modules reuse doesn't crash the server.
+knot.add_module(None, ModStats())
+
 ctl = libknot.control.KnotCtl()
 
 ZONE_NAME = "testzone."