Crash: XDamageCreate on already-destroyed window causes BadDrawable fatal error

Summary

Muffin crashes with a fatal BadDrawable X error when a client rapidly creates and destroys override-redirect windows. The crash originates in create_damage() in src/compositor/meta-surface-actor-x11.c, where XDamageCreate is called without an X error trap.

Steps to Reproduce

1. Run an application under Wine 9.0 that rapidly creates/destroys override-redirect X11 windows (e.g. Altium Designer entering placement mode for pins, tracks, or lines)
2. Muffin crashes, all window decorations disappear, keyboard shortcuts stop working, no input possible in any window
3. Session manager tries to restart Cinnamon but fails ("respawning too quickly")

Error Output

(cinnamon:17468): Gdk-WARNING **: The program 'cinnamon' received an X Window System error.
The error was 'BadDrawable (invalid Pixmap or Window parameter)'.
  (Details: serial 5002 error_code 9 request_code 143 (DAMAGE) minor_code 1)

Also observed before the crash:

Window manager warning: WM_TRANSIENT_FOR window 0x50000c1 for 0x50000c4 window
override-redirect is an override-redirect window and this is not correct according
to the standard, so we'll fallback to the first non-override-redirect window 0x500004c.

Root Cause

In src/compositor/meta-surface-actor-x11.c, the create_damage() function (line 347) calls XDamageCreate without an X error trap:

static void
create_damage (MetaSurfaceActorX11 *self)
{
  Display *xdisplay = meta_x11_display_get_xdisplay (self->display->x11_display);
  Window xwindow = meta_window_x11_get_toplevel_xwindow (self->window);

  self->damage = XDamageCreate (xdisplay, xwindow, XDamageReportBoundingBox);
}

When a client destroys a window between the time Muffin receives the MapNotify event and the time it calls XDamageCreate, the X server returns BadDrawable, which is treated as a fatal error and crashes Cinnamon.

Notably, XDamageDestroy in the same file (line 82-85) is already protected with meta_x11_error_trap_push/pop:

meta_x11_error_trap_push (display->x11_display);
XDamageDestroy (xdisplay, self->damage);
self->damage = None;
meta_x11_error_trap_pop (display->x11_display);

Proposed Fix

Wrap XDamageCreate with the same error trap pattern:

--- a/src/compositor/meta-surface-actor-x11.c
+++ b/src/compositor/meta-surface-actor-x11.c
@@ -349,7 +349,9 @@ create_damage (MetaSurfaceActorX11 *self)
   Display *xdisplay = meta_x11_display_get_xdisplay (self->display->x11_display);
   Window xwindow = meta_window_x11_get_toplevel_xwindow (self->window);
 
+  meta_x11_error_trap_push (self->display->x11_display);
   self->damage = XDamageCreate (xdisplay, xwindow, XDamageReportBoundingBox);
+  meta_x11_error_trap_pop (self->display->x11_display);
 }

This is a minimal, safe change — if the window no longer exists, the error is silently ignored and self->damage remains unset. This is the correct behavior since there is nothing to track damage on for a destroyed window.

Environment

• Muffin: 6.6.3+zena
• Cinnamon: Linux Mint 22
• Kernel: 6.17.0-14-generic
• GPU: AMD RDNA4 (amdgpu)
• Trigger application: Wine 9.0 running Altium Designer 16 (but any application rapidly creating/destroying override-redirect windows could trigger this)

Testing

The fix has been locally compiled and tested. With the patched libmuffin.so.0.0.0, the crash no longer occurs — Altium Designer placement operations work without affecting Cinnamon stability.

Read src/compositor/meta-surface-actor-x11.c, starting with create_damage() and the existing XDamageDestroy error-trap handling. Build Muffin and exercise the reported rapid window creation and destruction scenario under Wine. Done means the BadDrawable condition no longer causes a fatal Cinnamon crash and damage creation remains unset when the window has disappeared.