Cleanup the peer point formats on regotiation

Fixes openssl#14875

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from openssl#15383)

ssl/statem/extensions.c

@@ -45,6 +45,7 @@ static int tls_parse_certificate_authorities(SSL *s, PACKET *pkt,
 #ifndef OPENSSL_NO_SRP
 static int init_srp(SSL *s, unsigned int context);
 #endif
+static int init_ec_point_formats(SSL *s, unsigned int context);
 static int init_etm(SSL *s, unsigned int context);
 static int init_ems(SSL *s, unsigned int context);
 static int final_ems(SSL *s, unsigned int context, int sent);
@@ -159,7 +160,7 @@ static const EXTENSION_DEFINITION ext_defs[] = {
         TLSEXT_TYPE_ec_point_formats,
         SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
         | SSL_EXT_TLS1_2_AND_BELOW_ONLY,
-        NULL, tls_parse_ctos_ec_pt_formats, tls_parse_stoc_ec_pt_formats,
+        init_ec_point_formats, tls_parse_ctos_ec_pt_formats, tls_parse_stoc_ec_pt_formats,
         tls_construct_stoc_ec_pt_formats, tls_construct_ctos_ec_pt_formats,
         final_ec_pt_formats
     },
@@ -1145,6 +1146,15 @@ static int init_srp(SSL *s, unsigned int context)
 }
 #endif
 
+static int init_ec_point_formats(SSL *s, unsigned int context)
+{
+    OPENSSL_free(s->ext.peer_ecpointformats);
+    s->ext.peer_ecpointformats = NULL;
+    s->ext.peer_ecpointformats_len = 0;
+
+    return 1;
+}
+
 static int init_etm(SSL *s, unsigned int context)
 {
     s->ext.use_etm = 0;