Remove NULL checks before calling free

We (and OpenSSL) already use calling free on null pointers in a number
of places and also C99 standards says free(NULL) does nothing.

The if (x) free(x) calls more often make code harder to read, instead
of easier, remove these NULL checks in favour of directly calling
free(x).

The OpenSSL *_free methods are also safe to call with NULL and
pkcs11h_certificate_freeCertificateIdList is also safe to be called with
NULL.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20201023113431.26691-5-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg21216.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

sample/sample-plugins/client-connect/sample-client-connect.c

@@ -173,10 +173,7 @@ openvpn_plugin_open_v3(const int v3structver,
     return OPENVPN_PLUGIN_FUNC_SUCCESS;
 
 error:
-    if (context)
-    {
-        free(context);
-    }
+    free(context);
     return OPENVPN_PLUGIN_FUNC_ERROR;
 }
 

src/openvpn/buffer.c

@@ -184,10 +184,7 @@ buf_assign(struct buffer *dest, const struct buffer *src)
 void
 free_buf(struct buffer *buf)
 {
-    if (buf->data)
-    {
-        free(buf->data);
-    }
+    free(buf->data);
     CLEAR(*buf);
 }
 

src/openvpn/error.c

@@ -488,11 +488,8 @@ close_syslog(void)
     {
         closelog();
         use_syslog = false;
-        if (pgmname_syslog)
-        {
-            free(pgmname_syslog);
-            pgmname_syslog = NULL;
-        }
+        free(pgmname_syslog);
+        pgmname_syslog = NULL;
     }
 #endif
 }

src/openvpn/init.c

@@ -3597,14 +3597,9 @@ do_close_tls(struct context *c)
     }
 
     /* free options compatibility strings */
-    if (c->c2.options_string_local)
-    {
-        free(c->c2.options_string_local);
-    }
-    if (c->c2.options_string_remote)
-    {
-        free(c->c2.options_string_remote);
-    }
+    free(c->c2.options_string_local);
+    free(c->c2.options_string_remote);
+
     c->c2.options_string_local = c->c2.options_string_remote = NULL;
 
     if (c->c2.pulled_options_state)

src/openvpn/manage.c

@@ -826,14 +826,8 @@ man_pkcs11_id_get(struct management *man, const int index)
         msg(M_CLIENT, ">PKCS11ID-ENTRY:'%d'", index);
     }
 
-    if (id != NULL)
-    {
-        free(id);
-    }
-    if (base64 != NULL)
-    {
-        free(base64);
-    }
+    free(id);
+    free(base64);
 }
 
 #endif /* ifdef ENABLE_PKCS11 */
@@ -2613,10 +2607,7 @@ man_connection_close(struct management *man)
 {
     struct man_connection *mc = &man->connection;
 
-    if (mc->es)
-    {
-        event_free(mc->es);
-    }
+    event_free(mc->es);
 #ifdef _WIN32
     net_event_win32_close(&mc->ne32);
 #endif
@@ -2629,14 +2620,10 @@ man_connection_close(struct management *man)
     {
         man_close_socket(man, mc->sd_cli);
     }
-    if (mc->in)
-    {
-        command_line_free(mc->in);
-    }
-    if (mc->out)
-    {
-        buffer_list_free(mc->out);
-    }
+
+    command_line_free(mc->in);
+    buffer_list_free(mc->out);
+
     in_extra_reset(&man->connection, IER_RESET);
     buffer_list_free(mc->ext_key_input);
     man_connection_clear(mc);
@@ -3896,6 +3883,10 @@ command_line_reset(struct command_line *cl)
 void
 command_line_free(struct command_line *cl)
 {
+    if (!cl)
+    {
+        return;
+    }
     command_line_reset(cl);
     free_buf(&cl->buf);
     free_buf(&cl->residual);
@@ -4015,10 +4006,8 @@ log_entry_print(const struct log_entry *e, unsigned int flags, struct gc_arena *
 static void
 log_entry_free_contents(struct log_entry *e)
 {
-    if (e->string)
-    {
-        free((char *)e->string);
-    }
+    /* Cast away constness of const char* */
+    free((char *)e->string);
     CLEAR(*e);
 }
 

src/openvpn/mtcp.c

@@ -229,10 +229,7 @@ multi_tcp_free(struct multi_tcp *mtcp)
     if (mtcp)
     {
         event_free(mtcp->es);
-        if (mtcp->esr)
-        {
-            free(mtcp->esr);
-        }
+        free(mtcp->esr);
         free(mtcp);
     }
 }

src/openvpn/multi.c

@@ -73,10 +73,7 @@ id(struct multi_instance *mi)
 static void
 set_cc_config(struct multi_instance *mi, struct buffer_list *cc_config)
 {
-    if (mi->cc_config)
-    {
-        buffer_list_free(mi->cc_config);
-    }
+    buffer_list_free(mi->cc_config);
     mi->cc_config = cc_config;
 }
 #endif
@@ -4016,10 +4013,7 @@ management_client_pf(void *arg,
         ret = pf_load_from_buffer_list(&mi->context, pf_config);
     }
 
-    if (pf_config)
-    {
-        buffer_list_free(pf_config);
-    }
+    buffer_list_free(pf_config);
     return ret;
 }
 #endif /* ifdef MANAGEMENT_PF */

src/openvpn/packet_id.c

@@ -103,10 +103,7 @@ packet_id_free(struct packet_id *p)
     if (p)
     {
         dmsg(D_PID_DEBUG, "PID packet_id_free");
-        if (p->rec.seq_list)
-        {
-            free(p->rec.seq_list);
-        }
+        free(p->rec.seq_list);
         CLEAR(*p);
     }
 }

src/openvpn/pkcs11.c

@@ -461,11 +461,8 @@ pkcs11_management_id_count(void)
 
 cleanup:
 
-    if (id_list != NULL)
-    {
-        pkcs11h_certificate_freeCertificateIdList(id_list);
-        id_list = NULL;
-    }
+    pkcs11h_certificate_freeCertificateIdList(id_list);
+    id_list = NULL;
 
     dmsg(
         D_PKCS11_DEBUG,
@@ -630,29 +627,17 @@ pkcs11_management_id_get(
 
 cleanup:
 
-    if (id_list != NULL)
-    {
-        pkcs11h_certificate_freeCertificateIdList(id_list);
-        id_list = NULL;
-    }
+    pkcs11h_certificate_freeCertificateIdList(id_list);
+    id_list = NULL;
 
-    if (internal_id != NULL)
-    {
-        free(internal_id);
-        internal_id = NULL;
-    }
+    free(internal_id);
+    internal_id = NULL;
 
-    if (internal_base64 != NULL)
-    {
-        free(internal_base64);
-        internal_base64 = NULL;
-    }
+    free(internal_base64);
+    internal_base64 = NULL;
 
-    if (certificate_blob != NULL)
-    {
-        free(certificate_blob);
-        certificate_blob = NULL;
-    }
+    free(certificate_blob);
+    certificate_blob = NULL;
 
     dmsg(
         D_PKCS11_DEBUG,
@@ -1005,19 +990,13 @@ cleanup1:
             certificate = NULL;
         }
 
-        if (ser != NULL)
-        {
-            free(ser);
-            ser = NULL;
-        }
+        free(ser);
+        ser = NULL;
     }
 
 cleanup:
-    if (user_certificates != NULL)
-    {
-        pkcs11h_certificate_freeCertificateIdList(user_certificates);
-        user_certificates = NULL;
-    }
+    pkcs11h_certificate_freeCertificateIdList(user_certificates);
+    user_certificates = NULL;
 
     pkcs11h_terminate();
     gc_free(&gc);

src/openvpn/pkcs11_openssl.c

@@ -102,17 +102,11 @@ cleanup:
      * openssl objects have reference
      * count, so release them
      */
-    if (x509 != NULL)
-    {
-        X509_free(x509);
-        x509 = NULL;
-    }
+    X509_free(x509);
+    x509 = NULL;
 
-    if (evp != NULL)
-    {
-        EVP_PKEY_free(evp);
-        evp = NULL;
-    }
+    EVP_PKEY_free(evp);
+    evp = NULL;
 
     if (openssl_session != NULL)
     {
@@ -138,11 +132,8 @@ pkcs11_certificate_dn(pkcs11h_certificate_t certificate, struct gc_arena *gc)
     dn = x509_get_subject(x509, gc);
 
 cleanup:
-    if (x509 != NULL)
-    {
-        X509_free(x509);
-        x509 = NULL;
-    }
+    X509_free(x509);
+    x509 = NULL;
 
     return dn;
 }
@@ -183,12 +174,9 @@ pkcs11_certificate_serial(pkcs11h_certificate_t certificate, char *serial,
     ret = 0;
 
 cleanup:
+    X509_free(x509);
+    x509 = NULL;
 
-    if (x509 != NULL)
-    {
-        X509_free(x509);
-        x509 = NULL;
-    }
     return ret;
 }
 #endif /* defined(ENABLE_PKCS11) && defined(ENABLE_OPENSSL) */

src/openvpn/proxy.c

@@ -366,10 +366,7 @@ get_proxy_authenticate(socket_descriptor_t sd,
 static void
 store_proxy_authenticate(struct http_proxy_info *p, char *data)
 {
-    if (p->proxy_authenticate)
-    {
-        free(p->proxy_authenticate);
-    }
+    free(p->proxy_authenticate);
     p->proxy_authenticate = data;
 }
 

src/openvpn/ssl.c

@@ -1105,10 +1105,7 @@ tls_session_free(struct tls_session *session, bool clear)
         key_state_free(&session->key[i], false);
     }
 
-    if (session->common_name)
-    {
-        free(session->common_name);
-    }
+    free(session->common_name);
 
     cert_hash_free(session->cert_hash_set);
 
@@ -1300,16 +1297,8 @@ tls_multi_free(struct tls_multi *multi, bool clear)
     auth_set_client_reason(multi, NULL);
 
     free(multi->peer_info);
-
-    if (multi->locked_cn)
-    {
-        free(multi->locked_cn);
-    }
-
-    if (multi->locked_username)
-    {
-        free(multi->locked_username);
-    }
+    free(multi->locked_cn);
+    free(multi->locked_username);
 
     cert_hash_free(multi->locked_cert_hash_set);
 

src/openvpn/ssl_mbedtls.c

@@ -138,53 +138,31 @@ tls_ctx_free(struct tls_root_ctx *ctx)
     if (ctx)
     {
         mbedtls_pk_free(ctx->priv_key);
-        if (ctx->priv_key)
-        {
-            free(ctx->priv_key);
-        }
+        free(ctx->priv_key);
 
         mbedtls_x509_crt_free(ctx->ca_chain);
-        if (ctx->ca_chain)
-        {
-            free(ctx->ca_chain);
-        }
+        free(ctx->ca_chain);
 
         mbedtls_x509_crt_free(ctx->crt_chain);
-        if (ctx->crt_chain)
-        {
-            free(ctx->crt_chain);
-        }
+        free(ctx->crt_chain);
 
         mbedtls_dhm_free(ctx->dhm_ctx);
-        if (ctx->dhm_ctx)
-        {
-            free(ctx->dhm_ctx);
-        }
+        free(ctx->dhm_ctx);
 
         mbedtls_x509_crl_free(ctx->crl);
-        if (ctx->crl)
-        {
-            free(ctx->crl);
-        }
+        free(ctx->crl);
 
 #if defined(ENABLE_PKCS11)
         pkcs11h_certificate_freeCertificate(ctx->pkcs11_cert);
 #endif
 
-        if (ctx->allowed_ciphers)
-        {
-            free(ctx->allowed_ciphers);
-        }
+        free(ctx->allowed_ciphers);
 
-        if (ctx->groups)
-        {
-            free(ctx->groups);
-        }
+        free(ctx->groups);
 
         CLEAR(*ctx);
 
         ctx->initialised = false;
-
     }
 }
 

src/openvpn/ssl_openssl.c

@@ -144,10 +144,7 @@ void
 tls_ctx_free(struct tls_root_ctx *ctx)
 {
     ASSERT(NULL != ctx);
-    if (NULL != ctx->ctx)
-    {
-        SSL_CTX_free(ctx->ctx);
-    }
+    SSL_CTX_free(ctx->ctx);
     ctx->ctx = NULL;
 }
 
@@ -978,14 +975,8 @@ end:
         crypto_print_openssl_errors(M_DEBUG);
     }
 
-    if (in != NULL)
-    {
-        BIO_free(in);
-    }
-    if (x)
-    {
-        X509_free(x);
-    }
+    BIO_free(in);
+    X509_free(x);
 }
 
 int
@@ -1044,14 +1035,8 @@ tls_ctx_load_priv_file(struct tls_root_ctx *ctx, const char *priv_key_file,
     ret = 0;
 
 end:
-    if (pkey)
-    {
-        EVP_PKEY_free(pkey);
-    }
-    if (in)
-    {
-        BIO_free(in);
-    }
+    EVP_PKEY_free(pkey);
+    BIO_free(in);
     return ret;
 }
 
@@ -1312,12 +1297,9 @@ err:
     {
         RSA_free(rsa);
     }
-    else
+    else if (rsa_meth)
     {
-        if (rsa_meth)
-        {
-            RSA_meth_free(rsa_meth);
-        }
+        RSA_meth_free(rsa_meth);
     }
     return 0;
 }
@@ -1441,14 +1423,8 @@ tls_ctx_use_external_ec_key(struct tls_root_ctx *ctx, EVP_PKEY *pkey)
 
 err:
     /* Reach here only when ec and privkey can be independenly freed */
-    if (privkey)
-    {
-        EVP_PKEY_free(privkey);
-    }
-    if (ec)
-    {
-        EC_KEY_free(ec);
-    }
+    EVP_PKEY_free(privkey);
+    EC_KEY_free(ec);
     return 0;
 }
 #endif /* OPENSSL_VERSION_NUMBER > 1.1.0 dev && !defined(OPENSSL_NO_EC) */
@@ -1645,10 +1621,7 @@ tls_ctx_load_ca(struct tls_root_ctx *ctx, const char *ca_file,
             }
         }
 
-        if (in)
-        {
-            BIO_free(in);
-        }
+        BIO_free(in);
     }
 
     /* Set a store for certs (CA & CRL) with a lookup on the "capath" hash directory */

src/openvpn/ssl_verify.c

@@ -841,11 +841,9 @@ cleanup:
 void
 auth_set_client_reason(struct tls_multi *multi, const char *client_reason)
 {
-    if (multi->client_reason)
-    {
-        free(multi->client_reason);
-        multi->client_reason = NULL;
-    }
+    free(multi->client_reason);
+    multi->client_reason = NULL;
+
     if (client_reason && strlen(client_reason))
     {
         multi->client_reason = string_alloc(client_reason, NULL);

src/openvpn/ssl_verify_openssl.c

@@ -372,11 +372,7 @@ x509_get_subject(X509 *cert, struct gc_arena *gc)
     subject[subject_mem->length] = '\0';
 
 err:
-    if (subject_bio)
-    {
-        BIO_free(subject_bio);
-    }
-
+    BIO_free(subject_bio);
     return subject;
 }
 

src/openvpn/status.c

@@ -203,10 +203,8 @@ status_close(struct status_output *so)
                 ret = false;
             }
         }
-        if (so->filename)
-        {
-            free(so->filename);
-        }
+        free(so->filename);
+
         if (buf_defined(&so->read_buf))
         {
             free_buf(&so->read_buf);

src/openvpn/tun.c

@@ -1835,10 +1835,8 @@ close_tun_generic(struct tuntap *tt)
     {
         close(tt->fd);
     }
-    if (tt->actual_name)
-    {
-        free(tt->actual_name);
-    }
+
+    free(tt->actual_name);
     clear_tuntap(tt);
 }
 #endif /* !_WIN32 */
@@ -2522,10 +2520,7 @@ close_tun(struct tuntap *tt, openvpn_net_ctx_t *ctx)
 
     solaris_close_tun(tt);
 
-    if (tt->actual_name)
-    {
-        free(tt->actual_name);
-    }
+    free(tt->actual_name);
 
     clear_tuntap(tt);
     free(tt);
@@ -6901,10 +6896,7 @@ close_tun(struct tuntap *tt, openvpn_net_ctx_t *ctx)
         }
     }
 
-    if (tt->actual_name)
-    {
-        free(tt->actual_name);
-    }
+    free(tt->actual_name);
 
     if (tt->windows_driver == WINDOWS_DRIVER_WINTUN)
     {

src/plugins/auth-pam/auth-pam.c

@@ -506,10 +506,7 @@ openvpn_plugin_open_v3(const int v3structver,
     }
 
 error:
-    if (context)
-    {
-        free(context);
-    }
+    free(context);
     return OPENVPN_PLUGIN_FUNC_ERROR;
 }
 

src/plugins/down-root/down-root.c

@@ -238,10 +238,7 @@ free_context(struct down_root_context *context)
 {
     if (context)
     {
-        if (context->command)
-        {
-            free(context->command);
-        }
+        free(context->command);
         free(context);
     }
 }