[goffice] Avoid writing to a NULL buffer for an invalid GOPixbuf.

[Jean Bréfort <jbrefort src gnome org>]

commit 7bc785433ececa5be3ed2fdc9e98d267c97d5da3
Author: Jean Brefort <jean brefort normalesup org>
Date:   Mon Jul 8 16:45:37 2013 +0200

    Avoid writing to a NULL buffer for an invalid GOPixbuf.

 ChangeLog                 |    5 +++++
 goffice/utils/go-pixbuf.c |    3 +++
 2 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index e8bce69..9aaa96c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2013-07-08  Jean Brefort  <jean brefort normalesup org>
 
+       * goffice/utils/go-pixbuf.c (go_pixbuf_save),
+       (go_pixbuf_load_data), (go_pixbuf_draw): avoid writing to a NULL buffer.
+
+2013-07-08  Jean Brefort  <jean brefort normalesup org>
+
        * goffice/utils/go-pixbuf.c (go_pixbuf_load_data): fix loading of image with
        invalid size or data. [#703740]
 
diff --git a/goffice/utils/go-pixbuf.c b/goffice/utils/go-pixbuf.c
index 0675249..cef0033 100644
--- a/goffice/utils/go-pixbuf.c
+++ b/goffice/utils/go-pixbuf.c
@@ -86,6 +86,7 @@ go_pixbuf_save (GOImage *image, GsfXMLOut *output)
        gsf_xml_out_add_int (output, "rowstride", pixbuf->rowstride);
        if (!image->data) {
                image->data = g_new0 (guint8, image->height * pixbuf->rowstride);
+               g_return_if_fail (image->data !=NULL);
                pixbuf_to_cairo (pixbuf);
        }
        gsf_xml_out_add_base64
@@ -111,6 +112,7 @@ go_pixbuf_load_data (GOImage *image, GsfXMLIn *xin)
        if (expected != length)
                g_critical ("Invalid image size, expected %lu bytes, got %lu", expected, length);
        image->data = g_malloc (expected);
+       g_return_if_fail (image->data !=NULL);
        memcpy (image->data, xin->content->str, (length < expected)? length: expected);
        if (length < expected) /* fill with 0 */
                memset (image->data + length, 0, expected - length);
@@ -125,6 +127,7 @@ go_pixbuf_draw (GOImage *image, cairo_t *cr)
                if (image->data == NULL) {
                        /* image built from a pixbuf */
                        image->data = g_new0 (guint8, image->height * pixbuf->rowstride);
+                       g_return_if_fail (image->data !=NULL);
                        pixbuf_to_cairo (pixbuf);
                }
                pixbuf->surface = cairo_image_surface_create_for_data (image->data,