From 652a6b7ee1be26c1a5205a494b0245d41dc34e26 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 10 Mar 2017 13:53:53 +0000
Subject: [PATCH] Check that the PSK extension is last
We need to check that the PSK extension in a ClientHello is the last one.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2896)
---
ssl/statem/extensions.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/ssl/statem/extensions.c b/ssl/statem/extensions.c
index fab9bcb3d4..ffacd41cf9 100644
--- a/ssl/statem/extensions.c
+++ b/ssl/statem/extensions.c
@@ -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;
--
2.25.1