From 71da91453899ba20b28ee9712620e323145a0ee5 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <[email protected]>
Date: Tue, 4 Oct 2016 18:56:45 +0200
Subject: [PATCH] unescape: avoid integer overflow

CVE-2016-8622

Bug: https://curl.haxx.se/docs/adv_20161102H.html
Reported-by: Cure53
---
 docs/libcurl/curl_easy_unescape.3 |  7 +++++--
 lib/dict.c                        | 10 +++++-----
 lib/escape.c                      | 10 ++++++++--
 3 files changed, 18 insertions(+), 9 deletions(-)

--- docs/libcurl/curl_easy_unescape.3
+++ docs/libcurl/curl_easy_unescape.3
@@ -3,11 +3,11 @@
 .\" *  Project                     ___| | | |  _ \| |
 .\" *                             / __| | | | |_) | |
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2015, Daniel Stenberg, <[email protected]>, et al.
+.\" * Copyright (C) 1998 - 2016, Daniel Stenberg, <[email protected]>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
 .\" * are also available at https://curl.haxx.se/docs/copyright.html.
 .\" *
@@ -38,11 +38,14 @@ their binary versions.
 If the \fBlength\fP argument is set to 0 (zero), \fIcurl_easy_unescape(3)\fP
 will use strlen() on the input \fIurl\fP string to find out the size.
 
 If \fBoutlength\fP is non-NULL, the function will write the length of the
 returned string in the integer it points to. This allows an escaped string
-containing %00 to still get used properly after unescaping.
+containing %00 to still get used properly after unescaping. Since this is a
+pointer to an \fIint\fP type, it can only return a value up to INT_MAX so no
+longer string can be unescaped if the string length is returned in this
+parameter.
 
 You must \fIcurl_free(3)\fP the returned string when you're done with it.
 .SH AVAILABILITY
 Added in 7.15.4 and replaces the old \fIcurl_unescape(3)\fP function.
 .SH RETURN VALUE
--- lib/dict.c
+++ lib/dict.c
@@ -3,11 +3,11 @@
  *  Project                     ___| | | |  _ \| |
  *                             / __| | | | |_) | |
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2015, Daniel Stenberg, <[email protected]>, et al.
+ * Copyright (C) 1998 - 2016, Daniel Stenberg, <[email protected]>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
  * are also available at https://curl.haxx.se/docs/copyright.html.
  *
@@ -50,11 +50,11 @@
 
 #include "urldata.h"
 #include <curl/curl.h>
 #include "transfer.h"
 #include "sendf.h"
-
+#include "escape.h"
 #include "progress.h"
 #include "strequal.h"
 #include "dict.h"
 #include "rawstr.h"
 #include "curl_memory.h"
@@ -94,16 +94,16 @@ const struct Curl_handler Curl_handler_dict = {
 static char *unescape_word(struct Curl_easy *data, const char *inputbuff)
 {
   char *newp;
   char *dictp;
   char *ptr;
-  int len;
+  size_t len;
   char ch;
   int olen=0;
 
-  newp = curl_easy_unescape(data, inputbuff, 0, &len);
-  if(!newp)
+  CURLcode result = Curl_urldecode(data, inputbuff, 0, &newp, &len, FALSE);
+  if(!newp || result)
     return NULL;
 
   dictp = malloc(((size_t)len)*2 + 1); /* add one for terminating zero */
   if(dictp) {
     /* According to RFC2229 section 2.2, these letters need to be escaped with
--- lib/escape.c
+++ lib/escape.c
@@ -222,12 +222,18 @@ char *curl_easy_unescape(struct Curl_easy *data, const char *string,
     size_t outputlen;
     CURLcode res = Curl_urldecode(data, string, inputlen, &str, &outputlen,
                                   FALSE);
     if(res)
       return NULL;
-    if(olen)
-      *olen = curlx_uztosi(outputlen);
+
+    if(olen) {
+      if(outputlen <= (size_t) INT_MAX)
+        *olen = curlx_uztosi(outputlen);
+      else
+        /* too large to return in an int, fail! */
+        Curl_safefree(str);
+    }
   }
   return str;
 }
 
 /* For operating systems/environments that use different malloc/free
-- 
2.9.3