[goffice] Fix crash in exponential smoothing with invalid y data. [#377]

[Jean Bréfort <jbrefort src gnome org>]

commit 428936189ef5367313a582462508125efb58be15
Author: Jean Brefort <jean brefort normalesup org>
Date:   Tue Jan 15 09:33:24 2019 +0100

    Fix crash in exponential smoothing with invalid y data. [#377]

 ChangeLog                          | 5 +++++
 NEWS                               | 3 +++
 plugins/smoothing/gog-exp-smooth.c | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)
---
diff --git a/ChangeLog b/ChangeLog
index 51889d00..ad8b4a1c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-01-15  Jean Brefort  <jean brefort normalesup org>
+
+       * plugins/smoothing/gog-exp-smooth.c (gog_exp_smooth_update): protect
+       against NULL y values. [#377]
+
 2018-11-24  Morten Welinder  <terra gnome org>
 
        * goffice/math/go-quad.c: Introspection fixes.
diff --git a/NEWS b/NEWS
index 32ab2a89..3cfea871 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,8 @@
 goffice 0.10.45:
 
+Jean:
+       * Fix crash in exponential smoothing with invalid y data. [#377]
+
 Morten:
        * Introspection fixes.
        * Work around gtk-doc bugs.
diff --git a/plugins/smoothing/gog-exp-smooth.c b/plugins/smoothing/gog-exp-smooth.c
index 06ce52f9..1522009c 100644
--- a/plugins/smoothing/gog-exp-smooth.c
+++ b/plugins/smoothing/gog-exp-smooth.c
@@ -103,7 +103,7 @@ gog_exp_smooth_update (GogObject *obj)
                return;
 
        nb = gog_series_get_xy_data (series, &x_vals, &y_vals);
-       if (nb == 0)
+       if (nb == 0 || y_vals == NULL)
                return;
        x = g_new (double, nb);
        y = g_new (double, nb);