#933 lxappearance: Segfault on execution

[Giovanni Santini]

As in title.

I am using ArchLinux and running the GTK+3 version of LXDE.

Untill recently, the package has worked well, however it suddenly stopped working.

I can do provide the core dump (catched from systemd) and additional information, just tell me what you need.

/ Giovanni

[Kira Bruneau]

I'm also seeing a SEGFAULT starting lxapperance with sway, and I think the root cause is the same.

There was some discussion about it here: https://github.com/NixOS/nixpkgs/issues/67697 . The crash occurs on the call to XInternAtom in check_lxsession.

[bill-auger]

i sent a patch to the mailing list which avoids the segfault
https://sourceforge.net/p/lxde/mailman/lxde-list/thread/20201030001824.6817b566%40parabola/#msg37140205

backtrace of 'lxappearance':

(gdb) run
Starting program: /usr/bin/lxappearance 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Detaching after fork from child process 26979]

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff6e4dfe0 in cairo_surface_get_content () from /usr/lib/libcairo.so.2
(gdb) bt
#0  0x00007ffff6e4dfe0 in cairo_surface_get_content () at /usr/lib/libcairo.so.2
#1  0x00007ffff7739d1c in gdk_pixbuf_get_from_surface () at /usr/lib/libgdk-3.so.0
#2  0x00007ffff5b14692 in preview_menu (theme=0x555555c26040) at src/preview.c:152
#3  preview_theme
    (name=<optimized out>, titlelayout=0x555555a7bdd0 "NLIMC", active_window_font=<optimized out>, inactive_window_font=<optimized out>, menu_title_font=<optimized out>, menu_item_font=<optimized out>, osd_active_font=0x555555b37b20, osd_inactive_font=0x5555558dff20) at src/preview.c:835
#4  0x00007ffff5b14f56 in preview_update_all () at src/preview_update.c:60
#5  0x00007ffff5b15707 in theme_load_all () at src/theme.c:242
#6  0x00007ffff5b12d04 in plugin_load (app=<optimized out>, lxappearance_builder=<optimized out>)
    at src/main.c:231
#7  0x000055555555d3a9 in plugins_init (builder=0x55555581cc60) at plugin.c:62
#8  0x0000555555559372 in main (argc=<optimized out>, argv=<optimized out>) at lxappearance.c:670
(gdb)

[bill-auger]

the proper fix is included below

i add this for the sake of completeness/documentation - if only this patch is applied, it would allow lxappearance to operate normally; but the functionality of preview.c is still broken using GTK3 (per https://sourceforge.net/p/lxde/bugs/768/) - i dont believe that the GTK3 implementation ever worked properly - i have re-worked and completed that feature, which would close #768; but my changes are under VCS, and i kept this patch separate for the sake of documentation - the changes related to #768, assume that the patch below is already applied

diff --git a/src/preview.c b/src/preview.c
index ada6eb3..a2fc63d 100644
--- a/src/preview.c
+++ b/src/preview.c
@@ -30,6 +30,8 @@
 #include <obrender/theme.h>

 #if GTK_CHECK_VERSION(3, 0, 0)
+#include <cairo/cairo.h>
+#include <cairo/cairo-xlib.h>
 #include <gdk/gdkx.h>
 #endif