config: settings_export() - Fix for null dereference

Found by Coverity, 40224 Explicit null dereferenced

diff --git a/src/config/config-request.c b/src/config/config-request.c
index d5a90f3acb1774fc48ea84c160bd98add98db10b..f77718920551e34226a8eef41bef2eb65479d18b 100644 (file)
--- a/src/config/config-request.c
+++ b/src/config/config-request.c
@@ -158,6 +158,28 @@ bool config_export_type(string_t *str, const void *value,
        return TRUE;
 }
 
+static const char *
+get_default_value(const char *old_default_value,
+                 const struct setting_parser_info *info,
+                 const struct setting_define *def)
+{
+       if (old_default_value != NULL)
+               return old_default_value;
+
+       const void *default_value =
+               CONST_PTR_OFFSET(info->defaults, def->offset);
+       string_t *value = t_str_new(64);
+       if (!config_export_type(value, default_value, def->type))
+               i_unreached();
+       if (def->type == SET_ENUM) {
+               /* enum begins with default: followed by other valid values */
+               const char *p = strchr(str_c(value), ':');
+               if (p != NULL)
+                       str_truncate(value, p - str_c(value));
+       }
+       return str_c(value);
+}
+
 static void
 settings_export(struct config_export_context *ctx,
                const struct config_module_parser *module_parser)
@@ -232,9 +254,8 @@ settings_export(struct config_export_context *ctx,
                case SET_STR:
                case SET_STR_NOVARS:
                case SET_ENUM: {
-                       string_t *default_str = NULL;
                        bool default_changed = FALSE;
-                       const char *old_default;
+                       const char *old_default = NULL;
                        i_assert(info->defaults != NULL);
                        if (module_parser->change_counters[define_idx] <= CONFIG_PARSER_CHANGE_DEFAULTS) {
                                /* Setting isn't explicitly set. We need to see
@@ -246,34 +267,12 @@ settings_export(struct config_export_context *ctx,
                                }
                                if (old_settings_default(ctx->dovecot_config_version,
                                                         def->key, key_with_path,
-                                                        &old_default)) {
-                                       default_str = t_str_new(strlen(old_default));
-                                       str_append(default_str, old_default);
+                                                        &old_default))
                                        default_changed = TRUE;
-                               }
                        }
 
-                       if ((!dump_default || module_parser->change_counters[define_idx] == 0) &&
-                           default_str == NULL) {
-                               const void *default_value =
-                                       CONST_PTR_OFFSET(info->defaults,
-                                                        def->offset);
-                               default_str = t_str_new(64);
-                               if (!config_export_type(default_str, default_value,
-                                                       def->type))
-                                       i_unreached();
-                               if (def->type == SET_ENUM) {
-                                       /* enum begins with default: followed
-                                          by other valid values */
-                                       const char *p = strchr(str_c(default_str), ':');
-                                       if (p != NULL) {
-                                               str_truncate(default_str,
-                                                       p - str_c(default_str));
-                                       }
-                               }
-                       }
                        if (!dump_default &&
-                           strcmp(str_c(default_str),
+                           strcmp(get_default_value(old_default, info, def),
                                   module_parser->settings[define_idx].str) == 0) {
                                /* Explicitly set setting value wasn't
                                   actually changed from its default. */
@@ -294,7 +293,8 @@ settings_export(struct config_export_context *ctx,
                                str_append(ctx->value,
                                        module_parser->settings[define_idx].str);
                        } else {
-                               str_append_str(ctx->value, default_str);
+                               str_append(ctx->value,
+                                       get_default_value(old_default, info, def));
                        }
                        dump = TRUE;
                        break;