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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6099C433EF for ; Thu, 4 Nov 2021 11:41:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD7C561205 for ; Thu, 4 Nov 2021 11:41:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231447AbhKDLn7 (ORCPT ); Thu, 4 Nov 2021 07:43:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230344AbhKDLn5 (ORCPT ); Thu, 4 Nov 2021 07:43:57 -0400 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3828EC061714; Thu, 4 Nov 2021 04:41:20 -0700 (PDT) Received: by mail-pl1-x632.google.com with SMTP id k4so6738028plx.8; Thu, 04 Nov 2021 04:41:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=n1KhtkqwaiQeXN8wz3FjznNjYcnDj30fnMJ2MENI/bM=; b=KQNGVR1HjSVGE5tz7qTLIvpjqQmLLIXvMhmUIX1v/H8T4POwg3YJlXuwBujn9osnWj zwUKG4bSbCO9BgN1ndXpwTOC4ZGshqEWCg2lUGB8mwheuuw3MsSD+l7jKUhCldT36KXy /k+r2TbeILGTORLc1FUyD7r1XJfAkLjs7d8jJLNGKjtvgQKr3is4JqDwRGIGopEq0+jX +hS5vJlUKgC6+8uTX9zIdpyTV+t1BCtqKYmSLRGeB2mg6auVXh9QJsVu2smc//mJfXY5 7l57qf1pd8uhCGqTG2XK/ogtCeD6SniUuGi1iWTUJbGpIuUuHxZeotOqwczi6Jm3sVPt /yGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=n1KhtkqwaiQeXN8wz3FjznNjYcnDj30fnMJ2MENI/bM=; b=1PkcShVkJHCCSzj+Dq+FSuRE5QAeMxV+F6ORLUi2HKqC/ebSqHCl2mTKrdYZCkJzSs uHMZMB224t271JpvfL9a8ZWAeUFI0NWrtIag9JQE9pqeAGi2WAZpPhyp6diU2c0+ch6k QG61p4CSG4PtLgstVmAN2CH4mJljkBtLiTcz6WYmauhYlzrmmjarqFqenWHR14aFrTVA xWPKemo7Y5Zmxu/1qtV53e68+2YRRuwopyVMhQtrVR/NBdtcIsnUeQCjdgvarecDBgMM vZchyMXEc0n+HldeBnLYuQ92iE4E9idGgKcF2dlAxdJJnGcv/syj0KqNwbPtaIlSs4yj huHA== X-Gm-Message-State: AOAM530iRUAVxkt8uYLv/DwdmyZi+eb1hCrhiuMGfY6piAZgjbBxD0ij H52O6/vOQoixRmhgFVA2aEkNLEke+2MHEgqZ8t+/SLoSTQ///w== X-Google-Smtp-Source: ABdhPJwOv4LPU3RKWOoS5+kuHDOdoN+7OnHiHrrn/6kVi403ziyQaRqP7FjghbHi7bOfN/2po0nV/z/t/BWcZAqGON0= X-Received: by 2002:a17:90a:b296:: with SMTP id c22mr21364719pjr.13.1636026079704; Thu, 04 Nov 2021 04:41:19 -0700 (PDT) MIME-Version: 1.0 References: <20211103071427.GA13854@raspberrypi> <7a71215c-58f4-081b-6a2e-030073f2737e@digikod.net> In-Reply-To: <7a71215c-58f4-081b-6a2e-030073f2737e@digikod.net> From: Austin Kim Date: Thu, 4 Nov 2021 20:41:10 +0900 Message-ID: Subject: Re: [PATCH] landlock: Initialize kernel stack variables properly To: =?UTF-8?B?TWlja2HDq2wgU2FsYcO8bg==?= Cc: "Serge E. Hallyn" , linux-security-module , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2021=EB=85=84 11=EC=9B=94 3=EC=9D=BC (=EC=88=98) =EC=98=A4=ED=9B=84 9:14, M= icka=C3=ABl Sala=C3=BCn =EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84= =B1: > > Hi Austin, > > On 03/11/2021 08:14, Austin Kim wrote: > > In case kernel stack variables are not initialized properly, there migh= t > > be a little chance of kernel information disclosure. So it is better fo= r > > kernel stack variables to be initialized with null characters. > > > > Signed-off-by: Austin Kim > > --- > > security/landlock/syscalls.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.= c > > index 32396962f04d..50a6f7091428 100644 > > --- a/security/landlock/syscalls.c > > +++ b/security/landlock/syscalls.c > > @@ -320,6 +320,8 @@ SYSCALL_DEFINE4(landlock_add_rule, > > if (rule_type !=3D LANDLOCK_RULE_PATH_BENEATH) > > return -EINVAL; > > > > + memset(&path_beneath_attr, 0, sizeof(path_beneath_attr)); > > + > > This memset is already done with the copy_from_user() call just below. > It seems that memset() is done inside copy_from_user(). Thanks for feedback. BR, Austin Kim > > /* Copies raw user space buffer, only one type for now. */ > > res =3D copy_from_user(&path_beneath_attr, rule_attr, > > sizeof(path_beneath_attr)); > >