[libxml2] Another variation of overflow in Conditional sections

[Daniel Veillard <veillard src gnome org>]

commit bd0526e66a56e75a18da8c15c4750db8f801c52d
Author: Daniel Veillard <veillard redhat com>
Date:   Fri Oct 23 19:02:28 2015 +0800

    Another variation of overflow in Conditional sections
    
    Which happen after the previous fix to
    https://bugzilla.gnome.org/show_bug.cgi?id=756456
    
    But stopping the parser and exiting we didn't pop the intermediary entities
    and doing the SKIP there applies on an input which may be too small

 parser.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/parser.c b/parser.c
index a65e4cc..b9217ff 100644
--- a/parser.c
+++ b/parser.c
@@ -6915,7 +6915,9 @@ xmlParseConditionalSections(xmlParserCtxtPtr ctxt) {
        "All markup of the conditional section is not in the same entity\n",
                                 NULL, NULL);
        }
-        SKIP(3);
+       if ((ctxt-> instate != XML_PARSER_EOF) &&
+           ((ctxt->input->cur + 3) < ctxt->input->end))
+           SKIP(3);
     }
 }