From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68C74C43331 for ; Wed, 1 Apr 2020 10:07:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 387E82078B for ; Wed, 1 Apr 2020 10:07:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728087AbgDAKHN (ORCPT ); Wed, 1 Apr 2020 06:07:13 -0400 Received: from mx2.suse.de ([195.135.220.15]:35790 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725860AbgDAKHN (ORCPT ); Wed, 1 Apr 2020 06:07:13 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 36190ABF6; Wed, 1 Apr 2020 10:07:11 +0000 (UTC) From: Richard Palethorpe To: linux-can@vger.kernel.org Cc: Richard Palethorpe , Kees Cook , netdev@vger.kernel.org, security@kernel.org, wg@grandegger.com, mkl@pengutronix.de, davem@davemloft.net Subject: [PATCH v2] slcan: Don't transmit uninitialized stack data in padding Date: Wed, 1 Apr 2020 12:06:39 +0200 Message-Id: <20200401100639.20199-1-rpalethorpe@suse.com> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org struct can_frame contains some padding which is not explicitly zeroed in slc_bump. This uninitialized data will then be transmitted if the stack initialization hardening feature is not enabled (CONFIG_INIT_STACK_ALL). This commit just zeroes the whole struct including the padding. Signed-off-by: Richard Palethorpe Fixes: a1044e36e457 ("can: add slcan driver for serial/USB-serial CAN adapters") Reviewed-by: Kees Cook Cc: linux-can@vger.kernel.org Cc: netdev@vger.kernel.org Cc: security@kernel.org Cc: wg@grandegger.com Cc: mkl@pengutronix.de Cc: davem@davemloft.net --- V2: Reviewed by Kees and Fixes tag added. As mentioned in V1; The following unfinished test can reproduce the bug: https://github.com/richiejp/ltp/blob/pty-slcan/testcases/kernel/pty/pty04.c drivers/net/can/slcan.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c index a3664281a33f..4dfa459ef5c7 100644 --- a/drivers/net/can/slcan.c +++ b/drivers/net/can/slcan.c @@ -148,7 +148,7 @@ static void slc_bump(struct slcan *sl) u32 tmpid; char *cmd = sl->rbuff; - cf.can_id = 0; + memset(&cf, 0, sizeof(cf)); switch (*cmd) { case 'r': @@ -187,8 +187,6 @@ static void slc_bump(struct slcan *sl) else return; - *(u64 *) (&cf.data) = 0; /* clear payload */ - /* RTR frames may have a dlc > 0 but they never have any data bytes */ if (!(cf.can_id & CAN_RTR_FLAG)) { for (i = 0; i < cf.can_dlc; i++) { -- 2.24.0