1 files changed, 35 insertions, 25 deletions

diff --git a/lib/libssl/d1_both.c b/lib/libssl/d1_both.c
index 42f8cbd5370..074702153c8 100644
--- a/lib/libssl/d1_both.c
+++ b/lib/libssl/d1_both.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: d1_both.c,v 1.52 2017/10/08 16:24:02 jsing Exp $ */
+/* $OpenBSD: d1_both.c,v 1.53 2018/08/27 16:56:46 jsing Exp $ */
 /*
  * DTLS implementation written by Nagendra Modadugu
  * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
@@ -161,7 +161,8 @@ static unsigned int g_probable_mtu[] = {1500 - 28, 512 - 28, 256 - 28};
 static unsigned int dtls1_guess_mtu(unsigned int curr_mtu);
 static void dtls1_fix_message_header(SSL *s, unsigned long frag_off,
     unsigned long frag_len);
-static unsigned char *dtls1_write_message_header(SSL *s, unsigned char *p);
+static int dtls1_write_message_header(const struct hm_header_st *msg_hdr,
+    unsigned long frag_off, unsigned long frag_len, unsigned char *p);
 static long dtls1_get_message_fragment(SSL *s, int st1, int stn, long max,
     int *ok);
 
@@ -301,8 +302,10 @@ dtls1_do_write(SSL *s, int type)
 			dtls1_fix_message_header(s, frag_off,
 			    len - DTLS1_HM_HEADER_LENGTH);
 
-			dtls1_write_message_header(s,
-			    (unsigned char *)&s->internal->init_buf->data[s->internal->init_off]);
+			if (!dtls1_write_message_header(&D1I(s)->w_msg_hdr,
+			    D1I(s)->w_msg_hdr.frag_off, D1I(s)->w_msg_hdr.frag_len,
+			    (unsigned char *)&s->internal->init_buf->data[s->internal->init_off]))
+				return -1;
 
 			OPENSSL_assert(len >= DTLS1_HM_HEADER_LENGTH);
 		}
@@ -348,12 +351,9 @@ dtls1_do_write(SSL *s, int type)
 					 * Reconstruct message header is if it
 					 * is being sent in single fragment
 					 */
-					*p++ = msg_hdr->type;
-					l2n3(msg_hdr->msg_len, p);
-					s2n (msg_hdr->seq, p);
-					l2n3(0, p);
-					l2n3(msg_hdr->msg_len, p);
-					p -= DTLS1_HM_HEADER_LENGTH;
+					if (!dtls1_write_message_header(msg_hdr,
+					    0, msg_hdr->msg_len, p))
+						return (-1);
 					xlen = ret;
 				} else {
 					p += DTLS1_HM_HEADER_LENGTH;
@@ -431,13 +431,9 @@ again:
 	msg_len = msg_hdr->msg_len;
 
 	/* reconstruct message header */
-	*(p++) = msg_hdr->type;
-	l2n3(msg_len, p);
-	s2n (msg_hdr->seq, p);
-	l2n3(0, p);
-	l2n3(msg_len, p);
+	if (!dtls1_write_message_header(msg_hdr, 0, msg_len, p))
+		return -1;
 
-	p -= DTLS1_HM_HEADER_LENGTH;
 	msg_len += DTLS1_HM_HEADER_LENGTH;
 
 	tls1_finish_mac(s, p, msg_len);
@@ -1167,19 +1163,33 @@ dtls1_fix_message_header(SSL *s, unsigned long frag_off, unsigned long frag_len)
 	msg_hdr->frag_len = frag_len;
 }
 
-static unsigned char *
-dtls1_write_message_header(SSL *s, unsigned char *p)
+static int
+dtls1_write_message_header(const struct hm_header_st *msg_hdr,
+    unsigned long frag_off, unsigned long frag_len, unsigned char *p)
 {
-	struct hm_header_st *msg_hdr = &D1I(s)->w_msg_hdr;
+	CBB cbb;
 
-	*p++ = msg_hdr->type;
-	l2n3(msg_hdr->msg_len, p);
+	/* We assume DTLS1_HM_HEADER_LENGTH bytes are available for now... */
+	if (!CBB_init_fixed(&cbb, p, DTLS1_HM_HEADER_LENGTH))
+		return 0;
+	if (!CBB_add_u8(&cbb, msg_hdr->type))
+		goto err;
+	if (!CBB_add_u24(&cbb, msg_hdr->msg_len))
+		goto err;
+	if (!CBB_add_u16(&cbb, msg_hdr->seq))
+		goto err;
+	if (!CBB_add_u24(&cbb, frag_off))
+		goto err;
+	if (!CBB_add_u24(&cbb, frag_len))
+		goto err;
+	if (!CBB_finish(&cbb, NULL, NULL))
+		goto err;
 
-	s2n(msg_hdr->seq, p);
-	l2n3(msg_hdr->frag_off, p);
-	l2n3(msg_hdr->frag_len, p);
+	return 1;
 
-	return p;
+ err:
+	CBB_cleanup(&cbb);
+	return 0;
 }
 
 unsigned int