check return values for EVP_Digest*() APIs

Reviewed-by: Richard Levitte <levitte@openssl.org>
diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index be4ba9c..5eefa2a 100644
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -1890,9 +1890,12 @@
      * elsewhere in OpenSSL. The session ID is set to the SHA256 (or SHA1 is
      * SHA256 is disabled) hash of the ticket.
      */
-    EVP_Digest(s->session->tlsext_tick, ticklen,
-               s->session->session_id, &s->session->session_id_length,
-               EVP_sha256(), NULL);
+    if (!EVP_Digest(s->session->tlsext_tick, ticklen,
+                    s->session->session_id, &s->session->session_id_length,
+                    EVP_sha256(), NULL)) {
+        SSLerr(SSL_F_TLS_PROCESS_NEW_SESSION_TICKET, ERR_R_EVP_LIB);
+        goto err;
+    }
     return MSG_PROCESS_CONTINUE_READING;
  f_err:
     ssl3_send_alert(s, SSL3_AL_FATAL, al);