From 9b3a44b339f5962645558732fcc2ae6112d4b9fb Mon Sep 17 00:00:00 2001
From: Andrew <159703254+andrewsoonqn@users.noreply.github.com>
Date: Mon, 29 Jun 2026 15:24:21 +0800
Subject: [PATCH] Parse user print info on the UI thread to prevent heap
 corruption (#119)

get_user_print_info()'s HTTP fetch can run on a worker thread (e.g. BindJob),
but parse_user_print_info() mutates userMachineList (insert/erase/delete
MachineObject). on_machine_alive (SSDP) mutates the same maps on the UI thread
without locking, so parsing off-thread races the map and frees MachineObjects
out from under it -> heap corruption.

Keep all device-list mutation on the UI thread: parse inline when already on
the main thread, otherwise marshal via CallAfter so it stays serialized with
on_machine_alive.
---
 src/slic3r/GUI/DeviceCore/DevManager.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/slic3r/GUI/DeviceCore/DevManager.cpp b/src/slic3r/GUI/DeviceCore/DevManager.cpp
index 2d54b5c85f..aa4d360b97 100644
--- a/src/slic3r/GUI/DeviceCore/DevManager.cpp
+++ b/src/slic3r/GUI/DeviceCore/DevManager.cpp
@@ -851,7 +851,9 @@ namespace Slic3r
         int result = m_agent->get_user_print_info(&http_code, &body, provider);
         if (result == 0)
         {
-            parse_user_print_info(body);
+            // parse_user_print_info and on_machine_alive (SSDP for discovery) both mutate the same userMachineList map.
+            // on_machine_alive mutates the map on the UI thread, do the same for parse_user_print_info.
+            Slic3r::GUI::wxGetApp().CallAfter([this, body]() { parse_user_print_info(body); });
         }
     }