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Avoid crashes when displaying menu help-echo strings

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Use GC handles for help-echo strings instead of raw pointers.

* src/w32menu.c (add_menu_item): Store GC handles.
(w32_menu_display_help): Dereference the string.
(w32_free_submenu_strings): Free GC handles.
This commit is contained in:
Helmut Eller 2025-11-11 08:25:30 +01:00
parent 0da729a2fc
commit be4014aa80
1 changed files with 5 additions and 7 deletions
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12
src/w32menu.c
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@ -1622,21 +1622,16 @@ add_menu_item (HMENU menu, widget_value *wv, HMENU item)
/* Set help string for menu item. Leave it as a pointer to
a Lisp_String until it is ready to be displayed, since GC
can happen while menus are active. */
/* FIXME/igc: store a gc_handle in info.dwItemData */
Lisp_Object help = gc_handle_value (wv->help);
if (!NILP (help))
{
/* We use XUNTAG below because in a 32-bit build
--with-wide-int we cannot pass a Lisp_Object
via a DWORD member of MENUITEMINFO. */
/* As of Jul-2012, w32api headers say that dwItemData
has DWORD type, but that's a bug: it should actually
be ULONG_PTR, which is correct for 32-bit and 64-bit
Windows alike. MSVC headers get it right; hopefully,
MinGW headers will, too. */
eassert (STRINGP (help));
info.dwItemData = (ULONG_PTR) XUNTAG (help, Lisp_String,
struct Lisp_String);
info.dwItemData = (ULONG_PTR) gc_handle_for (help);
}
if (wv->button_type == BUTTON_TYPE_RADIO)
{
@ -1729,7 +1724,7 @@ w32_menu_display_help (HWND owner, HMENU menu, UINT item, UINT flags)
help =
info.dwItemData
? make_lisp_ptr ((void *) info.dwItemData, Lisp_String)
? gc_handle_value ((gc_handle) info.dwItemData)
: Qnil;
}
@ -1771,6 +1766,9 @@ w32_free_submenu_strings (HMENU menu)
#endif
local_free (info.dwItemData);
}
/* Free the help-echo handle. */
else if (info.dwItemData)
free_gc_handle ((gc_handle) info.dwItemData);
/* Recurse down submenus. */
if (info.hSubMenu)