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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 DC611C4332B for ; Mon, 25 Jan 2021 22:44:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9A0C20C56 for ; Mon, 25 Jan 2021 22:44:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731591AbhAYWnw (ORCPT ); Mon, 25 Jan 2021 17:43:52 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:53880 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732651AbhAYWm7 (ORCPT ); Mon, 25 Jan 2021 17:42:59 -0500 Received: from fsav101.sakura.ne.jp (fsav101.sakura.ne.jp [27.133.134.228]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 10PMgEK6033580; Tue, 26 Jan 2021 07:42:14 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav101.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav101.sakura.ne.jp); Tue, 26 Jan 2021 07:42:14 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav101.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 10PMgEOw033569 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Tue, 26 Jan 2021 07:42:14 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH] smackfs: restrict bytes count in smackfs write functions To: Casey Schaufler , Sabyrzhan Tasbolatov Cc: jmorris@namei.org, serge@hallyn.com, andreyknvl@google.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com, Michal Hocko References: <20210124143627.582115-1-snovitoll@gmail.com> <3f33d3a2-c84c-081f-c1c4-424e5eeeb8d2@schaufler-ca.com> From: Tetsuo Handa Message-ID: <3c35f7cc-1c8d-2fa0-6bc9-bde4e96017ce@i-love.sakura.ne.jp> Date: Tue, 26 Jan 2021 07:42:12 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <3f33d3a2-c84c-081f-c1c4-424e5eeeb8d2@schaufler-ca.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/01/26 3:08, Casey Schaufler wrote: > On 1/24/2021 6:36 AM, Sabyrzhan Tasbolatov wrote: >> syzbot found WARNINGs in several smackfs write operations where >> bytes count is passed to memdup_user_nul which exceeds >> GFP MAX_ORDER. Check count size if bigger SMK_LONGLABEL, >> for smk_write_syslog if bigger than PAGE_SIZE - 1. >> >> Reported-by: syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com >> Signed-off-by: Sabyrzhan Tasbolatov > > Thank you for the patch. Unfortunately, SMK_LONGLABEL isn't > the right value in some of these cases. > Since it uses sscanf(), I think that whitespaces must be excluded from upper limit check. I'm proposing adding __GFP_NOWARM on the memdup_user_nul() side at https://lkml.kernel.org/r/20210120103436.11830-1-penguin-kernel@I-love.SAKURA.ne.jp .