[455402] Fix potential hang with pattern acls.

Fix hang if pattern acl contains a %u but an anonymous client connect.

Thanks to Christoph Krey.

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=455402

ChangeLog.txt

@@ -64,6 +64,8 @@ Broker:
   restricted to the root user only. Closes bug #452914.
 - Usernames and topics given in ACL files can now include a space. Closes bug
   #431780.
+- Fix hang if pattern acl contains a %u but an anonymous client connect.
+  Closes bug #455402.
 
 Clients:
 - Both clients can now load default configuration options from a file.

src/security_default.c

@@ -265,6 +265,7 @@ int mosquitto_acl_check_default(struct mosquitto_db *db, struct mosquitto *conte
 		tlen = strlen(acl_root->topic);
 
 		if(acl_root->ucount && !context->username){
+			acl_root = acl_root->next;
 			continue;
 		}
 
@@ -306,7 +307,6 @@ int mosquitto_acl_check_default(struct mosquitto_db *db, struct mosquitto *conte
 			}
 		}
 
-
 		acl_root = acl_root->next;
 	}