Bug#749629: immediate segfault on kfreebsd

[Steven Chamberlain]

Package: mate-screensaver
Version: 1.8.0-3
Severity: important

Hi,

mate-screensaver has an interesting crash on kfreebsd, which I think
is worth noting in case it could ever happen on Linux too.

It immediately and reproducibly crashes as soon as I activate it with
mate-screensaver-command -a

I haven't done any configuration of mate-screensaver;  it is using
default settings.

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt full
#0  0x0000000000000000 in ?? ()
No symbol table info available.
#1  0x000000000041ab78 in gs_fade_reset (fade=0x66c340) at gs-fade.c:919
        i = 0
        __FUNCTION__ = "gs_fade_reset"
#2  0x000000000040f79f in unfade_idle (manager=0x6998e0) at gs-manager.c:1204
        __FUNCTION__ = "unfade_idle"
#3  0x000000080349d343 in ?? () from /lib/x86_64-kfreebsd-gnu/libglib-2.0.so.0
No symbol table info available.
#4  0x000000080349c925 in g_main_context_dispatch () from /lib/x86_64-kfreebsd-gnu/libglib-2.0.so.0
No symbol table info available.
#5  0x000000080349cc88 in ?? () from /lib/x86_64-kfreebsd-gnu/libglib-2.0.so.0
No symbol table info available.
#6  0x000000080349cf4a in g_main_loop_run () from /lib/x86_64-kfreebsd-gnu/libglib-2.0.so.0
No symbol table info available.
#7  0x0000000801009287 in gtk_main () from /usr/lib/x86_64-kfreebsd-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#8  0x000000000040a09e in main (argc=1, argv=0x7fffffffd658) at mate-screensaver.c:118
        monitor = 0x62dd60
        error = 0x0
        show_version = 0
        no_daemon = 1
        debug = 0
        entries = {{long_name = 0x41b02c "version", short_name = 0 '\000', flags = 0, arg = G_OPTION_ARG_NONE, arg_data = 0x625d20 <show_version.51027>, 
            description = 0x41b034 "Version of this application", arg_description = 0x0}, {long_name = 0x41b050 "no-daemon", short_name = 0 '\000', flags = 0, 
            arg = G_OPTION_ARG_NONE, arg_data = 0x625be0 <no_daemon.51028>, description = 0x41b05a "Don't become a daemon", arg_description = 0x0}, {
            long_name = 0x41b070 "debug", short_name = 0 '\000', flags = 0, arg = G_OPTION_ARG_NONE, arg_data = 0x625d1c <debug.51029>, 
            description = 0x41b076 "Enable debugging code", arg_description = 0x0}, {long_name = 0x0, short_name = 0 '\000', flags = 0, arg = G_OPTION_ARG_NONE, 
            arg_data = 0x0, description = 0x0, arg_description = 0x0}}
        __FUNCTION__ = "main"

The problem is the uninitialised fade_finish function pointer here:

#1  0x000000000041ab78 in gs_fade_reset (fade=0x66c340) at gs-fade.c:919
919                     fade->priv->screen_priv[i].fade_finish (fade, i);

Note the fade_type is actually FADE_TYPE_NONE:

(gdb) p *fade->priv->screen_priv
$3 = {fade_type = 0, num_ramps = 0, info = 0x0, rrscreen = 0x0, vmg = {red = 0, green = 0, blue = 0}, fade_setup = 0x0, fade_set_alpha_gamma = 0x0, fade_finish = 0x0}

I think because I don't have the XRANDR extension on the system I'm
testing with.  check_randr_extension would initialise
screen_priv->fade_finish otherwise.

-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'stable')
Architecture: kfreebsd-amd64 (x86_64)

Kernel: kFreeBSD 9.0-2-amd64-xenhvm
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages mate-screensaver depends on:
ii  dbus-x11                  1.6.14-1
ii  libatk1.0-0               2.8.0-2
ii  libc0.1                   2.18-5
ii  libcairo2                 1.12.14-5
ii  libdbus-1-3               1.6.14-1
ii  libdbus-glib-1-2          0.100.2-1
ii  libfontconfig1            2.11.0-1
ii  libfreetype6              2.4.9-1.1
ii  libgdk-pixbuf2.0-0        2.28.2-1
ii  libgl1-mesa-glx [libgl1]  9.2.2-1
ii  libglib2.0-0              2.40.0-3
ii  libgtk2.0-0               2.24.22-1
ii  libice6                   2:1.0.8-2
ii  libmate-desktop-2-17      1.8.1+dfsg1-1
ii  libmate-menu2             1.8.0-2
ii  libmatekbd4               1.8.0-2
ii  libnotify4                0.7.6-2
ii  libpam0g                  1.1.8-1
ii  libpango-1.0-0            1.36.2-2
ii  libpangocairo-1.0-0       1.36.2-2
ii  libpangoft2-1.0-0         1.36.2-2
ii  libsm6                    2:1.2.1-2
ii  libstartup-notification0  0.12-3
ii  libx11-6                  2:1.6.1-1
ii  libxext6                  2:1.3.2-1
ii  libxklavier16             5.2.1-1
ii  libxss1                   1:1.2.2-1
ii  libxxf86vm1               1:1.1.3-1
ii  mate-screensaver-common   1.8.0-3
ii  mate-session-manager      1.8.1-2

Versions of packages mate-screensaver recommends:
pn  mate-power-manager  <none>

Versions of packages mate-screensaver suggests:
pn  rss-glx            <none>
pn  xscreensaver-data  <none>

-- no debconf information