https://bugs.gentoo.org/959434
https://bugs.debian.org/984953
https://gitlab.gnome.org/GNOME/gparted/-/issues/282
https://gitlab.gnome.org/GNOME/gparted/-/commit/6cd9690426ba576a22a5a48cae5684c542629591

From 6cd9690426ba576a22a5a48cae5684c542629591 Mon Sep 17 00:00:00 2001
From: Mike Fleetwood <mike.fleetwood@googlemail.com>
Date: Sun, 1 Jun 2025 15:08:57 +0100
Subject: [PATCH] Fix crash from dereferencing a nullptr in Utils::mk_pixbuf()
 (#282)

Debian bug 984953 [1] reported a crash from a nullptr dereference.  The
captured backtrace was:
    (gdb) backtrace
    #0  Gdk::Pixbuf::gobj (this=0x0) at ../gdkmm/pixbuf.h:389
    #1  Gdk::Pixbuf::get_width (this=0x0) at pixbuf.cc:517
    #2  0x0000aaaaaab89ca4 in GParted::Utils::mk_pixbuf (widget=..., stock_id=..., icon_size=..., icon_size@entry=...) at /usr/include/glibmm-2.4/glibmm/refptr.h:259
    #3  0x0000aaaaaab92020 in GParted::Win_GParted::refresh_combo_devices (this=0xffffffffe960) at /usr/include/gtkmm-3.0/gtkmm/enums.h:2870
    #4  0x0000aaaaaab95980 in GParted::Win_GParted::menu_gparted_refresh_devices (this=<optimized out>) at Win_GParted.cc:1674
    #5  0x0000aaaaaab95e2c in GParted::Win_GParted::initial_device_refresh (data=<optimized out>) at Win_GParted.cc:1605
    #6  0x0000fffff6b8dab4 in g_main_dispatch (context=0xaaaaaaca6f10) at ../../../glib/gmain.c:3325
    #7  g_main_context_dispatch (context=0xaaaaaaca6f10) at ../../../glib/gmain.c:4043
    #8  0x0000fffff6b8de5c in g_main_context_iterate (context=0xaaaaaaca6f10, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../glib/gmain.c:4119
    #9  0x0000fffff6b8e1b0 in g_main_loop_run (loop=loop@entry=0xaaaaabb23860) at ../../../glib/gmain.c:4317
    #10 0x0000fffff70b98f0 in gtk_main () at ../../../../gtk/gtkmain.c:1328
    #11 0x0000aaaaaab2138c in main (argc=<optimized out>, argv=<optimized out>) at main.cc:62

GParted is still using Gtk stock icons.  All attempts at re-creating
this crash by deleting icon files failed because if the desktop theme
doesn't provide the icons, the Gtk library falls back on using the
builtin copies of the stock icons instead.  It is unknown how the
reported managed to trigger this crash.  The only known way to reproduce
this crash is by changing the GParted source code to request a
non-existent stock icon.  This change was used:
         {
             //combo...
             treerow = *( liststore_devices ->append() ) ;
    +        static const Gtk::BuiltinStockID UNKNOWN = { ((GtkStock)"unknown") };
             treerow[ treeview_devices_columns .icon ] =
    -            Utils::mk_pixbuf(*this, Gtk::Stock::HARDDISK, Gtk::ICON_SIZE_LARGE_TOOLBAR);
    +            Utils::mk_pixbuf(*this, UNKNOWN, Gtk::ICON_SIZE_LARGE_TOOLBAR);
             treerow[ treeview_devices_columns .device ] = devices[ i ] .get_path() ;
             treerow[ treeview_devices_columns .size ] = "(" + Utils::format_size( devices[ i ] .length, devices[ i ] .sector_size ) + ")" ;

The bug in Utils::mk_pixbuf() is that render_icon_pixbuf() returned a
nullptr and was then dereferenced a few lines lower by
theme_icon->get_width().

Testing this fix with the above crash reproducing change applied results
in the GUI simply not showing an icon with each device name in the
device combo box selector.

[1] libgtkmm-3.0-1v5: GParted crashes on Gdk::Pixbuf::get_width()
    const ()
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=984953

Closes #282 - Crash due to not checking for failure to load icon
---
 src/Utils.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/Utils.cc b/src/Utils.cc
index 4c4d781a..a9c2e3e1 100644
--- a/src/Utils.cc
+++ b/src/Utils.cc
@@ -177,6 +177,8 @@ Glib::RefPtr<Gdk::Pixbuf> Utils::mk_pixbuf(Gtk::Widget& widget,
                                            Gtk::IconSize icon_size)
 {
 	Glib::RefPtr<Gdk::Pixbuf> theme_icon = widget.render_icon_pixbuf(stock_id, icon_size);
+	if (! theme_icon)
+		return theme_icon;
 
 	// Ensure icon size
 	int width = 0;
-- 
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