TLSv1.2: Treat zero-length fragments as invalid, unless they are application data
TLS v1.2 explicitly disallows other kinds of zero length fragments (earlier standards
don't mention zero-length fragments at all).
@@ -2133,6 +2133,16 @@ static int ssl_decrypt_buf( mbedtls_ssl_context *ssl )
if( ssl->in_msglen == 0 )
{
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+ if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3
+ && ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
+ {
+ /* TLS v1.2 explicitly disallows zero-length messages which are not application data */
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid zero-length message type: %d", ssl->in_msgtype ) );
+ return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+ }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
ssl->nb_zero++;
/*
