tls_process_server_hello: Disallow repeated HRR

Repeated HRR must be rejected.

Fixes #17934

Reviewed-by: Todd Short <todd.short@me.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17936)

diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index 1c4889431aa529af9b29cf610f68a1b980c342a9..5341a89dfc0aded01c158a1f7c45b755154dd122 100644 (file)
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -1395,6 +1395,10 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL *s, PACKET *pkt)
             && sversion == TLS1_2_VERSION
             && PACKET_remaining(pkt) >= SSL3_RANDOM_SIZE
             && memcmp(hrrrandom, PACKET_data(pkt), SSL3_RANDOM_SIZE) == 0) {
+        if (s->hello_retry_request != SSL_HRR_NONE) {
+            SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
+            goto err;
+        }
         s->hello_retry_request = SSL_HRR_PENDING;
         hrr = 1;
         if (!PACKET_forward(pkt, SSL3_RANDOM_SIZE)) {