From f48d9d4a955d7e4c1c692099ab67e1dbfeb51137 Mon Sep 17 00:00:00 2001
From: djm <>
Date: Thu, 5 Jan 2012 23:01:39 +0000
Subject: OpenSSL 1.0.0f: merge

---
 src/lib/libssl/d1_pkt.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

(limited to 'src/lib/libssl/d1_pkt.c')

diff --git a/src/lib/libssl/d1_pkt.c b/src/lib/libssl/d1_pkt.c
index 39aac73e10..e0c0f0cc9a 100644
--- a/src/lib/libssl/d1_pkt.c
+++ b/src/lib/libssl/d1_pkt.c
@@ -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)
 		{
-		/* decryption failed, silently discard message */
-		if (enc_err < 0)
-			{
-			rr->length = 0;
-			s->packet_length = 0;
-			}
-		goto 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)
 		{
-- 
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