[libxml2] Fix null deref in xmlreader buffer

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 0571b4e6073d5afbd0f4682e0486e655e347e0da
Author: zhouzhongyuan <zhouzhongyuan huawei com>
Date:   Fri Aug 9 15:39:17 2019 +0800

    Fix null deref in xmlreader buffer

 xmlreader.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/xmlreader.c b/xmlreader.c
old mode 100644
new mode 100755
index ebf3ca15..d7150710
--- a/xmlreader.c
+++ b/xmlreader.c
@@ -1716,6 +1716,8 @@ xmlTextReaderReadInnerXml(xmlTextReaderPtr reader ATTRIBUTE_UNUSED)
     }
     doc = reader->node->doc;
     buff = xmlBufferCreate();
+    if (buff == NULL)
+        return NULL;
     for (cur_node = reader->node->children; cur_node != NULL;
          cur_node = cur_node->next) {
         /* XXX: Why is the node copied? */