http://cvs.openssl.org/chngview?cn=21931

--- ssl/d1_pkt.c	2011-01-04 19:33:22.000000000 +0000
+++ ssl/d1_pkt.c.oden	2012-01-09 15:18:39.000000000 +0000
@@ -375,6 +375,7 @@ dtls1_process_record(SSL *s)
 	SSL3_RECORD *rr;
 	unsigned int mac_size;
 	unsigned char md[EVP_MAX_MD_SIZE];
+	int decryption_failed_or_bad_record_mac = 0;
 
 
 	rr= &(s->s3->rrec);
@@ -409,13 +410,10 @@ dtls1_process_record(SSL *s)
 	enc_err = s->method->ssl3_enc->enc(s,0);
 	if (enc_err <= 0)
 		{
-		if (enc_err == 0)
-			/* SSLerr() and ssl3_send_alert() have been called */
-			goto err;
-
-		/* otherwise enc_err == -1 */
-		al=SSL_AD_BAD_RECORD_MAC;
-		goto f_err;
+		/* To minimize information leaked via timing, we will always
+		 * perform all computations before discarding the message.
+		 */
+		decryption_failed_or_bad_record_mac = 1;
 		}
 
 #ifdef TLS_DEBUG
@@ -445,7 +443,7 @@ printf("\n");
 			SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_PRE_MAC_LENGTH_TOO_LONG);
 			goto f_err;
 #else
-			goto err;
+			decryption_failed_or_bad_record_mac = 1;
 #endif			
 			}
 		/* check the MAC for rr->input (it's in mac_size bytes at the tail) */
@@ -456,17 +454,25 @@ printf("\n");
 			SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_LENGTH_TOO_SHORT);
 			goto f_err;
 #else
-			goto err;
+			decryption_failed_or_bad_record_mac = 1;
 #endif
 			}
 		rr->length-=mac_size;
 		i=s->method->ssl3_enc->mac(s,md,0);
 		if (i < 0 || memcmp(md,&(rr->data[rr->length]),mac_size) != 0)
 			{
-			goto err;
+			decryption_failed_or_bad_record_mac = 1;
 			}
 		}
 
+	if (decryption_failed_or_bad_record_mac)
+		{
+		/* decryption failed, silently discard message */
+		rr->length = 0;
+		s->packet_length = 0;
+		goto err;
+		}
+
 	/* r->length is now just compressed */
 	if (s->expand != NULL)
 		{