From 6218ded6001ea330e589f92b6b2fa12777752b5d Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Thu, 16 Apr 2015 23:52:04 +0200
Subject: [PATCH] fix_hostname: zero length host name caused -1 index offset
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If a URL is given with a zero-length host name, like in "http://:80" or
just ":80", `fix_hostname()` will index the host name pointer with a -1
offset (as it blindly assumes a non-zero length) and both read and
assign that address.

CVE-2015-3144

Bug: http://curl.haxx.se/docs/adv_20150422D.html
Reported-by: Hanno Böck
---
 lib/url.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/url.c b/lib/url.c
index ee3d176..f033dbc 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -3625,11 +3625,11 @@ static void fix_hostname(struct SessionHandle *data,
 
   /* set the name we use to display the host name */
   host->dispname = host->name;
 
   len = strlen(host->name);
-  if(host->name[len-1] == '.')
+  if(len && (host->name[len-1] == '.'))
     /* strip off a single trailing dot if present, primarily for SNI but
        there's no use for it */
     host->name[len-1]=0;
 
   if(!is_ASCII_name(host->name)) {
-- 
2.1.4