Description: CVE-2014-2525: Fixes heap overflow in yaml_parser_scan_uri_escapes
  The heap overflow is caused by not properly expanding a string before
  writing to it in function yaml_parser_scan_uri_escapes in scanner.c. 

Origin: backport, https://bitbucket.org/xi/libyaml/commits/bce8b60f0b9af69fa9fab3093d0a41ba243de048
Author: Salvatore Bonaccorso <carnil@debian.org>
Last-Update: 2014-03-20
Applied-Upstream: 0.1.6

--- LibYAML/scanner.c
+++ LibYAML/scanner.c
@@ -2619,6 +2619,9 @@ yaml_parser_scan_tag_uri(yaml_parser_t *
         /* Check if it is a URI-escape sequence. */
 
         if (CHECK(parser->buffer, '%')) {
+            if (!STRING_EXTEND(parser, string))
+                goto error;
+
             if (!yaml_parser_scan_uri_escapes(parser,
                         directive, start_mark, &string)) goto error;
         }
--- LibYAML/yaml_private.h
+++ LibYAML/yaml_private.h
@@ -132,9 +132,12 @@ yaml_string_join(
      (string).start = (string).pointer = (string).end = 0)
 
 #define STRING_EXTEND(context,string)                                           \
-    (((string).pointer+5 < (string).end)                                        \
+    ((((string).pointer+5 < (string).end)                                       \
         || yaml_string_extend(&(string).start,                                  \
-            &(string).pointer, &(string).end))
+            &(string).pointer, &(string).end)) ?                                \
+         1 :                                                                    \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
 
 #define CLEAR(context,string)                                                   \
     ((string).pointer = (string).start,                                         \