commit 26b9172a50f1ad22ed94f9d11834ca75d380fe73
author Matt Caswell <matt@openssl.org> Thu May 11 11:31:57 2017 +0100
committer Matt Caswell <matt@openssl.org> Thu May 11 13:13:04 2017 +0100
tree 79b5bf52c4d3d1332c4e20d5462f54f068b56832
parent b6fdc12d94d7527c3018492ab838cbcda81ba346

Add some checks for trailing data after extension blocks

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3436)

ssl/statem/statem_clnt.c

diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index 73dcff6..b9b8da1 100644
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -1365,7 +1365,8 @@
     /* TLS extensions */
     if (PACKET_remaining(pkt) == 0) {
         PACKET_null_init(&extpkt);
-    } else if (!PACKET_as_length_prefixed_2(pkt, &extpkt)) {
+    } else if (!PACKET_as_length_prefixed_2(pkt, &extpkt)
+               || PACKET_remaining(pkt) != 0) {
         al = SSL_AD_DECODE_ERROR;
         SSLerr(SSL_F_TLS_PROCESS_SERVER_HELLO, SSL_R_BAD_LENGTH);
         goto f_err;
@@ -2517,6 +2518,7 @@
         PACKET extpkt;
 
         if (!PACKET_as_length_prefixed_2(pkt, &extpkt)
+                || PACKET_remaining(pkt) != 0
                 || !tls_collect_extensions(s, &extpkt,
                                            SSL_EXT_TLS1_3_NEW_SESSION_TICKET,
                                            &exts, &al, NULL, 1)
@@ -3474,7 +3476,8 @@
     PACKET extensions;
     RAW_EXTENSION *rawexts = NULL;
 
-    if (!PACKET_as_length_prefixed_2(pkt, &extensions)) {
+    if (!PACKET_as_length_prefixed_2(pkt, &extensions)
+            || PACKET_remaining(pkt) != 0) {
         al = SSL_AD_DECODE_ERROR;
         SSLerr(SSL_F_TLS_PROCESS_ENCRYPTED_EXTENSIONS, SSL_R_LENGTH_MISMATCH);
         goto err;