Check that the PSK extension is last
We need to check that the PSK extension in a ClientHello is the last one.
@@ -447,10 +447,14 @@ int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
}
/*
* Verify this extension is allowed. We only check duplicates for
- * extensions that we recognise.
+ * extensions that we recognise. We also have a special case for the
+ * PSK extension, which must be the last one in the ClientHello.
*/
if (!verify_extension(s, context, type, exts, raw_extensions, &thisex)
- || (thisex != NULL && thisex->present == 1)) {
+ || (thisex != NULL && thisex->present == 1)
+ || (type == TLSEXT_TYPE_psk
+ && (context & EXT_CLIENT_HELLO) != 0
+ && PACKET_remaining(&extensions) != 0)) {
SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_BAD_EXTENSION);
*al = SSL_AD_ILLEGAL_PARAMETER;
goto err;
