[libxml2] Fix memory leak in xmlParseEntityDecl error path

[Nick Wellnhofer <nwellnhof src gnome org>]

commit bedbef806531543712cf671e8805f4badf1a22ca
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Fri Jun 9 15:10:13 2017 +0200

    Fix memory leak in xmlParseEntityDecl error path
    
    When parsing the entity value, it can happen that an external entity
    with an unsupported encoding is loaded and the parser is stopped. This
    would lead to a memory leak.
    
    A custom SAX callback could also stop the parser.
    
    Found with libFuzzer and ASan.

 parser.c |   16 ++++++++--------
 1 files changed, 8 insertions(+), 8 deletions(-)
---
diff --git a/parser.c b/parser.c
index a5da1e4..d07d3e6 100644
--- a/parser.c
+++ b/parser.c
@@ -5713,7 +5713,7 @@ xmlParseEntityDecl(xmlParserCtxtPtr ctxt) {
            }
        }
        if (ctxt->instate == XML_PARSER_EOF)
-           return;
+           goto done;
        SKIP_BLANKS;
        if (RAW != '>') {
            xmlFatalErrMsgStr(ctxt, XML_ERR_ENTITY_NOT_FINISHED,
@@ -5744,17 +5744,17 @@ xmlParseEntityDecl(xmlParserCtxtPtr ctxt) {
                    cur = xmlSAX2GetEntity(ctxt, name);
                }
            }
-            if (cur != NULL) {
-               if (cur->orig != NULL)
-                   xmlFree(orig);
-               else
-                   cur->orig = orig;
-           } else
-               xmlFree(orig);
+            if ((cur != NULL) && (cur->orig == NULL)) {
+               cur->orig = orig;
+                orig = NULL;
+           }
        }
+
+done:
        if (value != NULL) xmlFree(value);
        if (URI != NULL) xmlFree(URI);
        if (literal != NULL) xmlFree(literal);
+        if (orig != NULL) xmlFree(orig);
     }
 }