Created attachment 294132 [details]
fix "success" argument to gdk_colormap_alloc_colors()

Looks as if this bug has been present since 2002, but I did not experience it until 2014.

I start gnucash, then select Actions > Scheduled Transactions > Scheduled Transaction Editor. Gnucash immediately stops with a segmentation fault.

The problem is an incorrect call to

gdk_colormap_alloc_colors(GdkColormap *colormap,
                          GdkColor *colors,
                          gint n_colors,
                          gboolean writeable,
                          gboolean best_match,
                          gboolean *success);

[See https://developer.gnome.org/gdk2/stable/gdk2-Colormaps-and-Colors.html#gdk-colormap-alloc-colors]

The final argument is supposed to be an array of gboolean with n_colors elements.
However, in gnc-dense-cal.c'gnc_dense_cal_init(), we have:

static void
gnc_dense_cal_init(GncDenseCal *dcal)
{
    gboolean colorAllocSuccess;
    [...]
    if (gdk_colormap_alloc_colors(gdk_colormap_get_system(),
                                  dcal->weekColors,
                                  MAX_COLORS, TRUE, TRUE,
                                  &colorAllocSuccess) > 0)

On my system, this error caused dcal to get overwritten (gdk_colormap_alloc_colors() expected colorAllocSuccess to be bigger) and the subsequent call

    layout = gtk_widget_create_pango_layout(GTK_WIDGET(dcal), NULL);

caused a segmentation fault because dcal was no longer valid.

The attached patch changes colorAllocSuccess to an array of size MAX_COLORS.