When you expect a function to return a particular value, don't put a comment

saying that you expect it to return that value and compare it against zero
because it is supposedly faster, for this leads to bugs (especially given the
high rate of sloppy cut'n'paste within ssl3 and dtls1 routines in this
library).

Instead, compare for the exact value it ought to return upon success.

ok deraadt@

1 files changed, 4 insertions, 2 deletions

diff --git a/src/lib/libssl/d1_pkt.c b/src/lib/libssl/d1_pkt.c
index c9ffab1f3c..5be89f0955 100644
--- a/src/lib/libssl/d1_pkt.c
+++ b/src/lib/libssl/d1_pkt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: d1_pkt.c,v 1.32 2014/07/10 08:51:14 tedu Exp $ */
+/* $OpenBSD: d1_pkt.c,v 1.33 2014/08/07 19:46:31 miod Exp $ */
 /* 
  * DTLS implementation written by Nagendra Modadugu
  * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.  
@@ -414,10 +414,12 @@ dtls1_process_record(SSL *s)
                 }
 
                 i = s->method->ssl3_enc->mac(s, md, 0 /* not send */);
-                if (i < 0 || mac == NULL || timingsafe_memcmp(md, mac, (size_t)mac_size) != 0)
+                if (i < 0 || mac == NULL ||
+                    timingsafe_memcmp(md, mac, (size_t)mac_size) != 0)
                         enc_err = -1;
                 if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
                         enc_err = -1;
+                OPENSSL_cleanse(&md, sizeof md);
         }
 
         if (enc_err < 0) {