From: Dr. Stephen Henson <steve@openssl.org>
Date: Fri, 20 Dec 2013 15:26:50 +0000 (+0000)
Subject: Fix DTLS retransmission from previous session.
X-Git-Tag: OpenSSL_1_0_2-beta1~118
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=80b6d97585511931d7e5d1cbf24bd19f34d88bda;p=openssl

Fix DTLS retransmission from previous session.

For DTLS we might need to retransmit messages from the previous session
so keep a copy of write context in DTLS retransmission buffers instead
of replacing it after sending CCS. CVE-2013-6450.
(cherry picked from commit 34628967f1e65dc8f34e000f0f5518e21afbfc7b)
---

diff --git a/ssl/d1_both.c b/ssl/d1_both.c
index f7947bd988..f0c5962949 100644
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.c
@@ -214,6 +214,12 @@ dtls1_hm_fragment_new(unsigned long frag_len, int reassembly)
 static void
 dtls1_hm_fragment_free(hm_fragment *frag)
 	{
+
+	if (frag->msg_header.is_ccs)
+		{
+		EVP_CIPHER_CTX_free(frag->msg_header.saved_retransmit_state.enc_write_ctx);
+		EVP_MD_CTX_destroy(frag->msg_header.saved_retransmit_state.write_hash);
+		}
 	if (frag->fragment) OPENSSL_free(frag->fragment);
 	if (frag->reassembly) OPENSSL_free(frag->reassembly);
 	OPENSSL_free(frag);
diff --git a/ssl/t1_enc.c b/ssl/t1_enc.c
index 9eac36aa05..78ce5256e3 100644
--- a/ssl/t1_enc.c
+++ b/ssl/t1_enc.c
@@ -414,15 +414,20 @@ int tls1_change_cipher_state(SSL *s, int which)
 			s->mac_flags |= SSL_MAC_FLAG_WRITE_MAC_STREAM;
 			else
 			s->mac_flags &= ~SSL_MAC_FLAG_WRITE_MAC_STREAM;
-		if (s->enc_write_ctx != NULL)
+		if (s->enc_write_ctx != NULL && !SSL_IS_DTLS(s))
 			reuse_dd = 1;
-		else if ((s->enc_write_ctx=OPENSSL_malloc(sizeof(EVP_CIPHER_CTX))) == NULL)
+		else if ((s->enc_write_ctx=EVP_CIPHER_CTX_new()) == NULL)
 			goto err;
-		else
-			/* make sure it's intialized in case we exit later with an error */
-			EVP_CIPHER_CTX_init(s->enc_write_ctx);
 		dd= s->enc_write_ctx;
-		mac_ctx = ssl_replace_hash(&s->write_hash,NULL);
+		if (SSL_IS_DTLS(s))
+			{
+			mac_ctx = EVP_MD_CTX_create();
+			if (!mac_ctx)
+				goto err;
+			s->write_hash = mac_ctx;
+			}
+		else
+			mac_ctx = ssl_replace_hash(&s->write_hash,NULL);
 #ifndef OPENSSL_NO_COMP
 		if (s->compress != NULL)
 			{