From 5c7ba42d2e90bdd94bb55c80d0787e998fad44f9 Mon Sep 17 00:00:00 2001
From: Baptiste Daroussin <bapt@FreeBSD.org>
Date: Mon, 3 Feb 2014 08:00:45 +0000
Subject: Apply patch for CVE-2013-6393 [1] to fix heap-based buffer overflow
 when parsing YAML tags. Also apply a patch for hardenning the guards againt
 the issue

The only user in base in yaml is pkg(7) which uses the library a way that it is not affected

Submitted by:	delphij
Obtained from:	https://bugzilla.redhat.com/show_bug.cgi?id=1033990
Security:	CVE-2013-6393
---
 src/api.c     |  7 ++++++-
 src/scanner.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 61 insertions(+), 9 deletions(-)

diff --git a/src/api.c b/src/api.c
index 0c4732e1520d..68bc2d8e9b0b 100644
--- a/src/api.c
+++ b/src/api.c
@@ -117,7 +117,12 @@ yaml_string_join(
 YAML_DECLARE(int)
 yaml_stack_extend(void **start, void **top, void **end)
 {
-    void *new_start = yaml_realloc(*start, ((char *)*end - (char *)*start)*2);
+    void *new_start;
+
+    if ((char *)*end - (char *)*start >= INT_MAX / 2)
+	return 0;
+
+    new_start = yaml_realloc(*start, ((char *)*end - (char *)*start)*2);
 
     if (!new_start) return 0;
 
diff --git a/src/scanner.c b/src/scanner.c
index a2e861926476..1aaadc40a004 100644
--- a/src/scanner.c
+++ b/src/scanner.c
@@ -615,11 +615,14 @@ yaml_parser_decrease_flow_level(yaml_parser_t *parser);
  */
 
 static int
-yaml_parser_roll_indent(yaml_parser_t *parser, int column,
+yaml_parser_roll_indent(yaml_parser_t *parser, size_t column,
         int number, yaml_token_type_t type, yaml_mark_t mark);
 
 static int
-yaml_parser_unroll_indent(yaml_parser_t *parser, int column);
+yaml_parser_unroll_indent(yaml_parser_t *parser, size_t column);
+
+static int
+yaml_parser_reset_indent(yaml_parser_t *parser);
 
 /*
  * Token fetchers.
@@ -1206,7 +1209,7 @@ yaml_parser_decrease_flow_level(yaml_parser_t *parser)
  */
 
 static int
-yaml_parser_roll_indent(yaml_parser_t *parser, int column,
+yaml_parser_roll_indent(yaml_parser_t *parser, size_t column,
         int number, yaml_token_type_t type, yaml_mark_t mark)
 {
     yaml_token_t token;
@@ -1216,7 +1219,7 @@ yaml_parser_roll_indent(yaml_parser_t *parser, int column,
     if (parser->flow_level)
         return 1;
 
-    if (parser->indent < column)
+    if (parser->indent == -1 || parser->indent < column)
     {
         /*
          * Push the current indentation level to the stack and set the new
@@ -1254,7 +1257,7 @@ yaml_parser_roll_indent(yaml_parser_t *parser, int column,
 
 
 static int
-yaml_parser_unroll_indent(yaml_parser_t *parser, int column)
+yaml_parser_unroll_indent(yaml_parser_t *parser, size_t column)
 {
     yaml_token_t token;
 
@@ -1263,6 +1266,15 @@ yaml_parser_unroll_indent(yaml_parser_t *parser, int column)
     if (parser->flow_level)
         return 1;
 
+    /*
+     * column is unsigned and parser->indent is signed, so if
+     * parser->indent is less than zero the conditional in the while
+     * loop below is incorrect.  Guard against that.
+     */
+    
+    if (parser->indent < 0)
+        return 1;
+
     /* Loop through the intendation levels in the stack. */
 
     while (parser->indent > column)
@@ -1282,6 +1294,41 @@ yaml_parser_unroll_indent(yaml_parser_t *parser, int column)
     return 1;
 }
 
+/*
+ * Pop indentation levels from the indents stack until the current
+ * level resets to -1.  For each intendation level, append the
+ * BLOCK-END token.
+ */
+
+static int
+yaml_parser_reset_indent(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* In the flow context, do nothing. */
+
+    if (parser->flow_level)
+        return 1;
+
+    /* Loop through the intendation levels in the stack. */
+
+    while (parser->indent > -1)
+    {
+        /* Create a token and append it to the queue. */
+
+        TOKEN_INIT(token, YAML_BLOCK_END_TOKEN, parser->mark, parser->mark);
+
+        if (!ENQUEUE(parser, parser->tokens, token))
+            return 0;
+
+        /* Pop the indentation level. */
+
+        parser->indent = POP(parser, parser->indents);
+    }
+
+    return 1;
+}
+
 /*
  * Initialize the scanner and produce the STREAM-START token.
  */
@@ -1338,7 +1385,7 @@ yaml_parser_fetch_stream_end(yaml_parser_t *parser)
 
     /* Reset the indentation level. */
 
-    if (!yaml_parser_unroll_indent(parser, -1))
+    if (!yaml_parser_reset_indent(parser))
         return 0;
 
     /* Reset simple keys. */
@@ -1369,7 +1416,7 @@ yaml_parser_fetch_directive(yaml_parser_t *parser)
 
     /* Reset the indentation level. */
 
-    if (!yaml_parser_unroll_indent(parser, -1))
+    if (!yaml_parser_reset_indent(parser))
         return 0;
 
     /* Reset simple keys. */
@@ -1407,7 +1454,7 @@ yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
 
     /* Reset the indentation level. */
 
-    if (!yaml_parser_unroll_indent(parser, -1))
+    if (!yaml_parser_reset_indent(parser))
         return 0;
 
     /* Reset simple keys. */
-- 
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