unescape: avoid integer overflow

CVE-2016-8622

Bug: https://curl.haxx.se/docs/adv_20161102H.html
Reported-by: Cure53
This commit is contained in:
Daniel Stenberg 2016-10-04 18:56:45 +02:00
parent c5be3d7267
commit 53e71e47d6
3 changed files with 18 additions and 9 deletions

View File

@ -5,7 +5,7 @@
.\" * | (__| |_| | _ <| |___
.\" * \___|\___/|_| \_\_____|
.\" *
.\" * 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
@ -40,7 +40,10 @@ 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

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@ -5,7 +5,7 @@
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* 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
@ -52,7 +52,7 @@
#include <curl/curl.h>
#include "transfer.h"
#include "sendf.h"
#include "escape.h"
#include "progress.h"
#include "strequal.h"
#include "dict.h"
@ -96,12 +96,12 @@ 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 */

View File

@ -224,8 +224,14 @@ char *curl_easy_unescape(struct Curl_easy *data, const char *string,
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;
}