Fix regression in setups without a client certificate

This fixes a null-pointer dereference in tls_ctx_cert_time(), which will
occur on clients that do not use a client certificate (ie that only have
auth-user-pass in the config, but no key and cert).  This bug was
introduced by commit 091edd8e on the master branch, and commit dfd940bb
on the release/2.3 branch.

This bug was found by chipitsine and reported in trac ticket #644.

While touching this function, I also made this function conform to the
openvpn coding style.

v2 - fix memory leak in builds using pre-1.0.2 openssl

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1451814476-32574-1-git-send-email-steffan@karger.me>
URL: http://article.gmane.org/gmane.network.openvpn.devel/10921
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
index 0a7f14b0bec6021b5d6da4760099e7c706096bad..d2f40e7788d6e0034d2acdb51ea80a69aee5a3eb 100644 (file)
--- a/src/openvpn/ssl_openssl.c
+++ b/src/openvpn/ssl_openssl.c
@@ -356,15 +356,22 @@ tls_ctx_check_cert_time (const struct tls_root_ctx *ctx)
   int ret;
   const X509 *cert;
 
+  ASSERT (ctx);
+
 #if OPENSSL_VERSION_NUMBER >= 0x10002000L
   /* OpenSSL 1.0.2 and up */
-  cert = SSL_CTX_get0_certificate(ctx->ctx);
+  cert = SSL_CTX_get0_certificate (ctx->ctx);
 #else
   /* OpenSSL 1.0.1 and earlier need an SSL object to get at the certificate */
-  SSL *ssl = SSL_new(ctx->ctx);
-  cert = SSL_get_certificate(ssl);
+  SSL *ssl = SSL_new (ctx->ctx);
+  cert = SSL_get_certificate (ssl);
 #endif
 
+  if (cert == NULL)
+    {
+      goto cleanup; /* Nothing to check if there is no certificate */
+    }
+
   ret = X509_cmp_time (X509_get_notBefore (cert), NULL);
   if (ret == 0)
     {
@@ -384,9 +391,12 @@ tls_ctx_check_cert_time (const struct tls_root_ctx *ctx)
     {
       msg (M_WARN, "WARNING: Your certificate has expired!");
     }
+
+cleanup:
 #if OPENSSL_VERSION_NUMBER < 0x10002000L
-  SSL_free(ssl);
+  SSL_free (ssl);
 #endif
+  return;
 }
 
 void

diff --git a/src/openvpn/ssl_polarssl.c b/src/openvpn/ssl_polarssl.c
index d7a40d772a731954542279d11e4144f174cae74d..339d1fb194fea9a70e0c442e49c0ea947d25cd37 100644 (file)
--- a/src/openvpn/ssl_polarssl.c
+++ b/src/openvpn/ssl_polarssl.c
@@ -218,6 +218,12 @@ tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers)
 void
 tls_ctx_check_cert_time (const struct tls_root_ctx *ctx)
 {
+  ASSERT (ctx);
+  if (ctx->crt_chain == NULL)
+    {
+      return; /* Nothing to check if there is no certificate */
+    }
+
   if (x509_time_future (&ctx->crt_chain->valid_from))
     {
       msg (M_WARN, "WARNING: Your certificate is not yet valid!");