cert-cred: fix possible segfault when resetting cert retrieval function

Reset get_cert_callback3 callback to NULL if provided callback is NULL.
Otherwise after the certificate request call_legacy_cert_cb1 /
call_legacy_cert_cb2 will try to unconditionally call legacy_cert_cb1 /
legacy_cert_cb2 callback (set to NULL) leading to segfault.

Fixes: 9829ef9a3ca06d60472599df7c74ebb9a53f1fe2
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>

diff --git a/lib/cert-cred.c b/lib/cert-cred.c
index d3777e51ffbb17ee5f6dcee8c03d5182634fc23e..c219e6e353e1691284837e7669cbe698348ec8b8 100644 (file)
--- a/lib/cert-cred.c
+++ b/lib/cert-cred.c
@@ -503,7 +503,10 @@ void gnutls_certificate_set_retrieve_function
      gnutls_certificate_retrieve_function * func)
 {
        cred->legacy_cert_cb1 = func;
-       cred->get_cert_callback3 = call_legacy_cert_cb1;
+       if (!func)
+               cred->get_cert_callback3 = NULL;
+       else
+               cred->get_cert_callback3 = call_legacy_cert_cb1;
 }
 
 static int call_legacy_cert_cb2(gnutls_session_t session,
@@ -578,7 +581,10 @@ void gnutls_certificate_set_retrieve_function2
      gnutls_certificate_retrieve_function2 * func) 
 {
        cred->legacy_cert_cb2 = func;
-       cred->get_cert_callback3 = call_legacy_cert_cb2;
+       if (!func)
+               cred->get_cert_callback3 = NULL;
+       else
+               cred->get_cert_callback3 = call_legacy_cert_cb2;
 }
 
 /**

diff --git a/tests/Makefile.am b/tests/Makefile.am
index f6d89ab6b347e5c87d33ff6bf46bf065a9bcc455..1081027c03667209a87b9fc3319065f8d740fc70 100644 (file)
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -197,7 +197,8 @@ ctests += mini-record-2 simple gnutls_hmac_fast set_pkcs12_cred cert certuniquei
         x509sign-verify-error rng-op-nonce rng-op-random rng-op-key x509-dn-decode-compat \
         ip-check mini-x509-ipaddr trust-store base64-raw random-art dhex509self \
         dss-sig-val sign-pk-api tls-session-ext-override record-pad \
-        tls13-server-kx-neg gnutls_ext_raw_parse_dtls key-export-pkcs8
+        tls13-server-kx-neg gnutls_ext_raw_parse_dtls key-export-pkcs8 \
+        null_retrieve_function
 
 if HAVE_SECCOMP_TESTS
 ctests += dtls-with-seccomp tls-with-seccomp dtls-client-with-seccomp tls-client-with-seccomp

diff --git a/tests/null_retrieve_function.c b/tests/null_retrieve_function.c
new file mode 100644 (file)
index 0000000..4eaee86
--- /dev/null
+++ b/tests/null_retrieve_function.c
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2011-2012 Free Software Foundation, Inc.
+ * Copyright (C) 2018 Dmitry Eremin-Solenikov
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GnuTLS; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/* Parts copied from GnuTLS example programs. */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <gnutls/gnutls.h>
+#include <gnutls/x509.h>
+#include <gnutls/abstract.h>
+
+#include "utils.h"
+#include "cert-common.h"
+
+/* Test for memory allocations in a non-matching key-cert pair loading.
+ *
+ */
+
+static int cert_cb1(gnutls_session_t session,
+               const gnutls_datum_t * req_ca_rdn,
+               int nreqs,
+               const gnutls_pk_algorithm_t * pk_algos,
+               int pk_algos_length,
+               gnutls_retr2_st *retr)
+{
+       return -1;
+}
+
+static int cert_cb2(gnutls_session_t session,
+               const gnutls_datum_t *req_ca_rdn,
+               int nreqs,
+               const gnutls_pk_algorithm_t *pk_algos,
+               int pk_algos_length,
+               gnutls_pcert_st** pcert,
+               unsigned int *pcert_length,
+               gnutls_privkey_t *privkey)
+{
+       return -1;
+}
+
+static int cert_cb3(gnutls_session_t session,
+               const struct gnutls_cert_retr_st *info,
+               gnutls_pcert_st **certs,
+               unsigned int *pcert_length,
+               gnutls_ocsp_data_st **ocsp,
+               unsigned int *ocsp_length,
+               gnutls_privkey_t *privkey,
+               unsigned int *flags)
+{
+       return -1;
+}
+
+
+static void tls_log_func(int level, const char *str)
+{
+       fprintf(stderr, "<%d>| %s", level, str);
+}
+
+void doit(void)
+{
+       gnutls_certificate_credentials_t x509_cred;
+       gnutls_certificate_credentials_t clicred;
+       int ret;
+
+       /* this must be called once in the program
+        */
+       global_init();
+
+       gnutls_global_set_log_function(tls_log_func);
+       if (debug)
+               gnutls_global_set_log_level(6);
+
+       gnutls_certificate_allocate_credentials(&x509_cred);
+
+       ret = gnutls_certificate_set_x509_key_mem(x509_cred, &server_ca3_localhost_cert_chain,
+                                           &server_ca3_key,
+                                           GNUTLS_X509_FMT_PEM);
+       if (ret < 0) {
+               fail("error in error code\n");
+               exit(1);
+       }
+
+       gnutls_certificate_allocate_credentials(&clicred);
+       gnutls_certificate_set_retrieve_function(clicred, cert_cb1);
+       gnutls_certificate_set_retrieve_function(clicred, NULL);
+       _test_cli_serv(x509_cred, clicred, "NORMAL", "NORMAL", "localhost", NULL, NULL, NULL, 0, 1, GNUTLS_E_NO_CERTIFICATE_FOUND, -1);
+       gnutls_certificate_free_credentials(clicred);
+
+       gnutls_certificate_allocate_credentials(&clicred);
+       gnutls_certificate_set_retrieve_function2(clicred, cert_cb2);
+       gnutls_certificate_set_retrieve_function2(clicred, NULL);
+       _test_cli_serv(x509_cred, clicred, "NORMAL", "NORMAL", "localhost", NULL, NULL, NULL, 0, 1, GNUTLS_E_NO_CERTIFICATE_FOUND, -1);
+       gnutls_certificate_free_credentials(clicred);
+
+       gnutls_certificate_allocate_credentials(&clicred);
+       gnutls_certificate_set_retrieve_function3(clicred, cert_cb3);
+       gnutls_certificate_set_retrieve_function3(clicred, NULL);
+       _test_cli_serv(x509_cred, clicred, "NORMAL", "NORMAL", "localhost", NULL, NULL, NULL, 0, 1, GNUTLS_E_NO_CERTIFICATE_FOUND, -1);
+       gnutls_certificate_free_credentials(clicred);
+
+       gnutls_certificate_free_credentials(x509_cred);
+
+       gnutls_global_deinit();
+
+       if (debug)
+               success("success");
+}