[openssl-dev] SSL_set_tlsext_host_name(ssl, "")

[Viktor Dukhovni]

On Sat, Jan 16, 2016 at 06:41:43PM +0000, Viktor Dukhovni wrote:

> > This can also be reproduced using
> > openssl s_client -servername "" ...
> 
> Please try the two attached patches.

Better version of the first patch.

-- 
	Viktor.
-------------- next part --------------
>From 792fd81abdffd068162077bdb972baccfe09f280 Mon Sep 17 00:00:00 2001
From: Viktor Dukhovni <openssl-users at dukhovni.org>
Date: Sat, 16 Jan 2016 12:57:24 -0500
Subject: [PATCH 1/2] Empty SNI names are not valid

While empty inputs to SSL_set1_host() clear the reference identifier
list.
---
 crypto/x509/x509_vpm.c | 4 ++--
 ssl/s3_lib.c           | 5 ++++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/crypto/x509/x509_vpm.c b/crypto/x509/x509_vpm.c
index 827360d..8826fec 100644
--- a/crypto/x509/x509_vpm.c
+++ b/crypto/x509/x509_vpm.c
@@ -92,11 +92,11 @@ static int int_x509_param_set_hosts(X509_VERIFY_PARAM *vpm, int mode,
      * Refuse names with embedded NUL bytes, except perhaps as final byte.
      * XXX: Do we need to push an error onto the error stack?
      */
-    if (namelen == 0)
+    if (namelen == 0 || name == NULL)
         namelen = name ? strlen(name) : 0;
     else if (name && memchr(name, '\0', namelen > 1 ? namelen - 1 : namelen))
         return 0;
-    if (name && name[namelen - 1] == '\0')
+    if (namelen > 0 && name[namelen - 1] == '\0')
         --namelen;
 
     if (mode == SET_HOST) {
diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index de8dae2..54b8eba 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -3534,13 +3534,16 @@ long ssl3_ctrl(SSL *s, int cmd, long larg, void *parg)
 #endif                          /* !OPENSSL_NO_EC */
     case SSL_CTRL_SET_TLSEXT_HOSTNAME:
         if (larg == TLSEXT_NAMETYPE_host_name) {
+            size_t len;
+
             OPENSSL_free(s->tlsext_hostname);
             s->tlsext_hostname = NULL;
 
             ret = 1;
             if (parg == NULL)
                 break;
-            if (strlen((char *)parg) > TLSEXT_MAXLEN_host_name) {
+            len = strlen((char *)parg);
+            if (len == 0 || len > TLSEXT_MAXLEN_host_name) {
                 SSLerr(SSL_F_SSL3_CTRL, SSL_R_SSL3_EXT_INVALID_SERVERNAME);
                 return 0;
             }
-- 
2.5.4 (Apple Git-61)