Use the correct size for TLSv1.3 finished keys

We need to use the length of the handshake hash for the length of the
finished key.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2157)

diff --git a/ssl/tls13_enc.c b/ssl/tls13_enc.c
index 5896a5f23971977faaf5d925001e942526f7a8a9..cbe989c6a2eb62a0c95027e3723a72e16391db34 100644 (file)
--- a/ssl/tls13_enc.c
+++ b/ssl/tls13_enc.c
@@ -330,7 +330,7 @@ int tls13_change_cipher_state(SSL *s, int which)
         if (which & SSL3_CC_HANDSHAKE) {
             insecret = s->handshake_secret;
             finsecret = s->client_finished_secret;
-            finsecretlen = sizeof(s->client_finished_secret);
+            finsecretlen = EVP_MD_size(ssl_handshake_md(s));
             label = client_handshake_traffic;
             labellen = sizeof(client_handshake_traffic) - 1;
         } else {
@@ -342,7 +342,7 @@ int tls13_change_cipher_state(SSL *s, int which)
         if (which & SSL3_CC_HANDSHAKE) {
             insecret = s->handshake_secret;
             finsecret = s->server_finished_secret;
-            finsecretlen = sizeof(s->server_finished_secret);
+            finsecretlen = EVP_MD_size(ssl_handshake_md(s));
             label = server_handshake_traffic;
             labellen = sizeof(server_handshake_traffic) - 1;
         } else {