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=-5.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=no 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 B1649C433E9 for ; Thu, 28 Jan 2021 13:28:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77DF664DD6 for ; Thu, 28 Jan 2021 13:28:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231927AbhA1N2J (ORCPT ); Thu, 28 Jan 2021 08:28:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229950AbhA1N2H (ORCPT ); Thu, 28 Jan 2021 08:28:07 -0500 Received: from mail-lj1-x236.google.com (mail-lj1-x236.google.com [IPv6:2a00:1450:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F469C061573; Thu, 28 Jan 2021 05:27:26 -0800 (PST) Received: by mail-lj1-x236.google.com with SMTP id f2so6281007ljp.11; Thu, 28 Jan 2021 05:27:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=8tvqUEPKnNcrsTtiavlBzi2ibquYTuocPU0umzSH5LI=; b=seuMePA/mnST1btiw896yyME8C3fNYkPM9VYQKEh5feuJ0tmW65ic7NwAqM8r4VvHL B8fsdPAnb/cScDv8Ssd+A9XUEMiL6377sCP9TdyE+PEVosdYRHqtNLU0ZM4dv4H3eSim ALVOjNb3MGsOSpoz+cC4dZ9JqL8b4g5kq21kbUDf1+7IPkKy1KI4ISsZIVY3u8LQLiq1 aomzPReExT48wDC2D+NCQwR31C0Lpb3zBv+alWb2Cavgvg1bBdfGITu1q1FF4zfNvN+H oanqmAxu6vym2j5hj4tXflpFFxiso4swJOHAkzvanW0ncMu7fgKgZywToqfZ16A4Pdoq Okeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=8tvqUEPKnNcrsTtiavlBzi2ibquYTuocPU0umzSH5LI=; b=bl5cr92OUU6UvAts03azeC7ne2sNmKdTeUoQenXn1Hgb2nIZAx856W2kO2thTj4c9E 75UIvky0jL4ycWWUnEOzhBuxfGv5suloZ5DXcOVQT+JIvnpebGejmoU2hicYY6exctRC MOXcbE8BxhL85G7gbNks93Ds+1dEVsbR/FOg6Ckq9KEKk+ZDf00PaGrhhqOsBeGxKrjN tgPZsFVEI/R5LF7Uel8Nbgxkxz18Yom+nnHJKa2BvRB85L1tespEH7UIaB1yVVkoPqq9 OANRGO8WPd17Z9TEtzOCT7s41RObMNEL+ul2mS8IFaMiXfSgP+fV6aHxkdN59Qi3YG4y FY8Q== X-Gm-Message-State: AOAM532HOro1Taj22vP80RggyhvTf+VchjTaK0weawEHGPUlBt7YPE0P jCsQXfgxn2CtZxBWBBK0C9Y= X-Google-Smtp-Source: ABdhPJzsiPTIa9b1AXsJ61Sto0REoDpd643CbZjruyzw88VOao4q8PSyQdxcyJbrPgiMAgAc5UFZjg== X-Received: by 2002:a05:651c:2112:: with SMTP id a18mr8568028ljq.341.1611840445011; Thu, 28 Jan 2021 05:27:25 -0800 (PST) Received: from localhost.localdomain ([5.76.199.233]) by smtp.googlemail.com with ESMTPSA id d12sm1610387lfm.163.2021.01.28.05.27.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Jan 2021 05:27:24 -0800 (PST) From: Sabyrzhan Tasbolatov To: penguin-kernel@i-love.sakura.ne.jp Cc: andreyknvl@google.com, casey@schaufler-ca.com, jmorris@namei.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, mhocko@suse.com, serge@hallyn.com, snovitoll@gmail.com, syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com Subject: Re: [PATCH v2] smackfs: restrict bytes count in smackfs write functions Date: Thu, 28 Jan 2021 19:27:21 +0600 Message-Id: <20210128132721.1111920-1-snovitoll@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <5271074f-930a-46e9-8ece-2cc65d45dc19@i-love.sakura.ne.jp> References: <5271074f-930a-46e9-8ece-2cc65d45dc19@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: > > /* > > + * No partial write. > > * Enough data must be present. > > */ > > if (*ppos != 0) > > return -EINVAL; > > + if (count == 0 || count > PAGE_SIZE) > > + return -EINVAL; > > > > data = memdup_user_nul(buf, count); > > if (IS_ERR(data)) > > > > Doesn't this change break legitimate requests like > > char buffer[20000]; > > memset(buffer, ' ', sizeof(buffer)); > memcpy(buffer + sizeof(buffer) - 10, "foo", 3); > write(fd, buffer, sizeof(buffer)); > > ? It does, in this case. Then I need to patch another version with whitespace stripping before, after label. I just followed the same thing that I see in security/selinux/selinuxfs.c sel_write_enforce() etc. It has the same memdup_user_nul() and count >= PAGE_SIZE check prior to that.