From 86d5f9ba4feb81337716c2c18ec753eb33c81d01 Mon Sep 17 00:00:00 2001
From: "Dr. Stephen Henson" <steve@openssl.org>
Date: Tue, 16 Nov 2010 13:26:24 +0000
Subject: [PATCH] fix CVE-2010-3864

---
 CHANGES      |  8 +++++++
 NEWS         |  1 +
 ssl/t1_lib.c | 60 ++++++++++++++++++++++++++++++++++++----------------
 3 files changed, 51 insertions(+), 18 deletions(-)

diff --git a/CHANGES b/CHANGES
index 80d0d4a67a..05c25aa3ae 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,10 @@
 
  Changes between 1.0.0a and 1.0.0b  [xx XXX xxxx]
 
+  *) Fix extension code to avoid race conditions which can result in a buffer
+     overrun vulnerability: resumed sessions must not be modified as they can
+     be shared by multiple threads. CVE-2010-3864
+
   *) Fix WIN32 build system to correctly link an ENGINE directory into
      a DLL. 
      [Steve Henson]
@@ -857,6 +861,10 @@
   
  Changes between 0.9.8o and 0.9.8p [xx XXX xxxx]
 
+  *) Fix extension code to avoid race conditions which can result in a buffer
+     overrun vulnerability: resumed sessions must not be modified as they can
+     be shared by multiple threads. CVE-2010-3864
+
   *) Fix for double free bug in ssl/s3_clnt.c CVE-2010-2939
      [Steve Henson]
 
diff --git a/NEWS b/NEWS
index a099d26317..23edac2e2b 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,7 @@
 
   Major changes between OpenSSL 1.0.0a and OpenSSL 1.0.0b:
 
+      o Fix for security issue CVE-2010-3864.
       o Fix for CVE-2010-2939
       o Fix WIN32 build system for GOST ENGINE.
 
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index e395287012..eea59163aa 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -714,14 +714,23 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
 				switch (servname_type)
 					{
 				case TLSEXT_NAMETYPE_host_name:
-					if (s->session->tlsext_hostname == NULL)
+					if (!s->hit)
 						{
-						if (len > TLSEXT_MAXLEN_host_name || 
-							((s->session->tlsext_hostname = OPENSSL_malloc(len+1)) == NULL))
+						if(s->session->tlsext_hostname)
+							{
+							*al = SSL_AD_DECODE_ERROR;
+							return 0;
+							}
+						if (len > TLSEXT_MAXLEN_host_name)
 							{
 							*al = TLS1_AD_UNRECOGNIZED_NAME;
 							return 0;
 							}
+						if ((s->session->tlsext_hostname = OPENSSL_malloc(len+1)) == NULL)
+							{
+							*al = TLS1_AD_INTERNAL_ERROR;
+							return 0;
+							}
 						memcpy(s->session->tlsext_hostname, sdata, len);
 						s->session->tlsext_hostname[len]='\0';
 						if (strlen(s->session->tlsext_hostname) != len) {
@@ -734,7 +743,8 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
 
 						}
 					else 
-						s->servername_done = strlen(s->session->tlsext_hostname) == len 
+						s->servername_done = s->session->tlsext_hostname
+							&& strlen(s->session->tlsext_hostname) == len 
 							&& strncmp(s->session->tlsext_hostname, (char *)sdata, len) == 0;
 					
 					break;
@@ -765,15 +775,22 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
 				*al = TLS1_AD_DECODE_ERROR;
 				return 0;
 				}
-			s->session->tlsext_ecpointformatlist_length = 0;
-			if (s->session->tlsext_ecpointformatlist != NULL) OPENSSL_free(s->session->tlsext_ecpointformatlist);
-			if ((s->session->tlsext_ecpointformatlist = OPENSSL_malloc(ecpointformatlist_length)) == NULL)
+			if (!s->hit)
 				{
-				*al = TLS1_AD_INTERNAL_ERROR;
-				return 0;
+				if(s->session->tlsext_ecpointformatlist)
+					{
+					*al = TLS1_AD_DECODE_ERROR;
+					return 0;
+					}
+				s->session->tlsext_ecpointformatlist_length = 0;
+				if ((s->session->tlsext_ecpointformatlist = OPENSSL_malloc(ecpointformatlist_length)) == NULL)
+					{
+					*al = TLS1_AD_INTERNAL_ERROR;
+					return 0;
+					}
+				s->session->tlsext_ecpointformatlist_length = ecpointformatlist_length;
+				memcpy(s->session->tlsext_ecpointformatlist, sdata, ecpointformatlist_length);
 				}
-			s->session->tlsext_ecpointformatlist_length = ecpointformatlist_length;
-			memcpy(s->session->tlsext_ecpointformatlist, sdata, ecpointformatlist_length);
 #if 0
 			fprintf(stderr,"ssl_parse_clienthello_tlsext s->session->tlsext_ecpointformatlist (length=%i) ", s->session->tlsext_ecpointformatlist_length);
 			sdata = s->session->tlsext_ecpointformatlist;
@@ -794,15 +811,22 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
 				*al = TLS1_AD_DECODE_ERROR;
 				return 0;
 				}
-			s->session->tlsext_ellipticcurvelist_length = 0;
-			if (s->session->tlsext_ellipticcurvelist != NULL) OPENSSL_free(s->session->tlsext_ellipticcurvelist);
-			if ((s->session->tlsext_ellipticcurvelist = OPENSSL_malloc(ellipticcurvelist_length)) == NULL)
+			if (!s->hit)
 				{
-				*al = TLS1_AD_INTERNAL_ERROR;
-				return 0;
+				if(s->session->tlsext_ellipticcurvelist)
+					{
+					*al = TLS1_AD_DECODE_ERROR;
+					return 0;
+					}
+				s->session->tlsext_ellipticcurvelist_length = 0;
+				if ((s->session->tlsext_ellipticcurvelist = OPENSSL_malloc(ellipticcurvelist_length)) == NULL)
+					{
+					*al = TLS1_AD_INTERNAL_ERROR;
+					return 0;
+					}
+				s->session->tlsext_ellipticcurvelist_length = ellipticcurvelist_length;
+				memcpy(s->session->tlsext_ellipticcurvelist, sdata, ellipticcurvelist_length);
 				}
-			s->session->tlsext_ellipticcurvelist_length = ellipticcurvelist_length;
-			memcpy(s->session->tlsext_ellipticcurvelist, sdata, ellipticcurvelist_length);
 #if 0
 			fprintf(stderr,"ssl_parse_clienthello_tlsext s->session->tlsext_ellipticcurvelist (length=%i) ", s->session->tlsext_ellipticcurvelist_length);
 			sdata = s->session->tlsext_ellipticcurvelist;
-- 
2.25.1