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From 71da91453899ba20b28ee9712620e323145a0ee5 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
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(-)
diff --git a/docs/libcurl/curl_easy_unescape.3 b/docs/libcurl/curl_easy_unescape.3
index 06fd6fc..50ce97d 100644
--- a/docs/libcurl/curl_easy_unescape.3
+++ b/docs/libcurl/curl_easy_unescape.3
@@ -3,11 +3,11 @@
.\" * Project ___| | | | _ \| |
.\" * / __| | | | |_) | |
.\" * | (__| |_| | _ <| |___
.\" * \___|\___/|_| \_\_____|
.\" *
-.\" * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, 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
diff --git a/lib/dict.c b/lib/dict.c
index a7b5965..48a4e0a 100644
--- a/lib/dict.c
+++ b/lib/dict.c
@@ -3,11 +3,11 @@
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
- * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, 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
diff --git a/lib/escape.c b/lib/escape.c
index e61260d..6657007 100644
--- a/lib/escape.c
+++ b/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
|