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=-2.1 required=3.0 tests=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_SANE_1 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 B969DC33C9E for ; Thu, 30 Jan 2020 06:57:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F32E206F0 for ; Thu, 30 Jan 2020 06:57:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Z/UuJZsH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726659AbgA3G5d (ORCPT ); Thu, 30 Jan 2020 01:57:33 -0500 Received: from mail-pf1-f175.google.com ([209.85.210.175]:40116 "EHLO mail-pf1-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725865AbgA3G5d (ORCPT ); Thu, 30 Jan 2020 01:57:33 -0500 Received: by mail-pf1-f175.google.com with SMTP id q8so990754pfh.7 for ; Wed, 29 Jan 2020 22:57:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=huaVosl53nJpP94v/buh4oiNNpbIxxq4KUuvCVKsRvg=; b=Z/UuJZsHzzCP0r8iNe0I5jcgDk7nS7QrCbZrFnip3NLgUewZWXkz4CQ1c/Q1cVT8Q1 +1GseJSJv2M3+mm4Hwh6Ywqx/ef7eZKb8Ct4LFiHcYQms0xoHXpeBixjapicNSPiDH2Q cZUNZMu6GBoHdBdPHOKZ+eLjW4QmBOYTEIjSCnpVEgdDOxp+N0DDFJLfNiZZHVnCAjss N2u6mfe98Z5Z7uZ9D1G5imSzIgGg0sdi3sTvRwBxM3ebVM2phop9IIH+wq3wqcaqd5No ZW9/7OPeZZ3UgnnBS9HCMoJjQz2PUr+zMfX9wjArH/BUNY7E167G8kLrPt+UOKjHP7P6 Uv9g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=huaVosl53nJpP94v/buh4oiNNpbIxxq4KUuvCVKsRvg=; b=W9CMXWcxM6AG4Hj61rTDPGlj4r1sX7Wu5C4nPr89uRq4qZ73Zj9vF1ymO1t2E1ZdsX 1/WNP5gWYb5YFeVh7DPy799XoI24+p/7GA44jbFk311RMB+IkNYw/Zz94tKvsxcNwZT8 2cQ1PZ/6qVoal1grzuX42eRW7f2Q7osHd+8Y+EPTXtLdxK8AiFliWSOysiZ6G/6pZTIg tNFhn56Yt3gsgSuiaP/h+oyZGvNoJk8TqPeMuXOMcaMQxwh60tvgyaqqUzMJ0wnORSO1 i1CpTD1xDOYB/A8WcR0BF9ZfcvZocBZ08qakeXKlQ9t32DhHPUcwhgpnr2xQYu7T9HBP 4v3g== X-Gm-Message-State: APjAAAVRgDZyNlzi9f1p0MdFIoeT58f0C8LEx3+olEtYu55c45CwKIyJ 8AL4psroGPR4aQurUUQ1994= X-Google-Smtp-Source: APXvYqyE7G6+WsXmD6yFeRj72KzFz7PcN7/o2vL2fDMibf6sPdxfm++Q7pFYY+JRKgQjAj5Os8ygXw== X-Received: by 2002:a63:8349:: with SMTP id h70mr3155850pge.396.1580367452803; Wed, 29 Jan 2020 22:57:32 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:5bbb:c872:f2b1:f53b]) by smtp.gmail.com with ESMTPSA id g8sm4970595pfh.43.2020.01.29.22.57.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jan 2020 22:57:32 -0800 (PST) Date: Thu, 30 Jan 2020 15:57:30 +0900 From: Sergey Senozhatsky To: Joe Perches Cc: Sergey Senozhatsky , Nathan Chancellor , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: -Wfortify-source in kernel/printk/printk.c Message-ID: <20200130065730.GG115889@google.com> References: <20200130021648.GA32309@ubuntu-x2-xlarge-x86> <20200130051711.GF115889@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/01/29 22:39), Joe Perches wrote: > > > It isn't wrong, given that when CONFIG_PRINTK is disabled, text's length > > > is 0 (LOG_LINE_MAX and PREFIX_MAX are both zero). How should this > > > warning be dealt this? I am not familiar enough with the printk code to > > > say myself. > > > > It's not wrong. > > > > Unless I'm missing something completely obvious: with disabled printk() > > we don't have any functions that can append messages to the logbuf, hence > > we can't overflow it. So the error in question should never trigger. > > > > - Normal printk() is void, so kernel cannot append messages; > > - dev_printk() is void, so drivers cannot append messages and dicts; > > - devkmsg_write() is void, so user space cannot write to logbuf. > > > > So I think we should never trigger that overflow (assuming that I > > didn't miss something) message. > > > > In any case feel free to submit a patch - switch it to snprintf(). > > and/or make the code depend on CONFIG_PRINTK console_unlock() still needs to at least up() the console semaphore. We don't have printk(), but the tty subsystem is still there and serial consoles and definitely still up and running. So... maybe we can have two versions of console_unlock(). -ss