From: Viktor Dukhovni <openssl-users@dukhovni.org>
Date: Wed, 28 Aug 2024 10:36:09 +0000 (+1000)
Subject: Check for excess data in CertificateVerify
X-Git-Tag: openssl-3.4.0-alpha1~24
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b4e4bf29ba3c67662c60ceed9afa2dd301e93273;p=thirdparty%2Fopenssl.git

Check for excess data in CertificateVerify

As reported by Alicja Kario, we ignored excess bytes after the
signature payload in TLS CertificateVerify Messages.  These
should not be present.

Fixes: #25298

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25302)
---

diff --git a/ssl/statem/statem_lib.c b/ssl/statem/statem_lib.c
index 8932ac44ca8..d52e2a73844 100644
--- a/ssl/statem/statem_lib.c
+++ b/ssl/statem/statem_lib.c
@@ -516,6 +516,10 @@ MSG_PROCESS_RETURN tls_process_cert_verify(SSL_CONNECTION *s, PACKET *pkt)
         SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_R_LENGTH_MISMATCH);
         goto err;
     }
+    if (PACKET_remaining(pkt) != 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_R_LENGTH_MISMATCH);
+        goto err;
+    }
 
     if (!get_cert_verify_tbs_data(s, tls13tbs, &hdata, &hdatalen)) {
         /* SSLfatal() already called */