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 A0F57C433F5 for ; Mon, 8 Nov 2021 11:58:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E6726120D for ; Mon, 8 Nov 2021 11:58:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239303AbhKHMAx (ORCPT ); Mon, 8 Nov 2021 07:00:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231401AbhKHMAw (ORCPT ); Mon, 8 Nov 2021 07:00:52 -0500 Received: from mail-lf1-x12d.google.com (mail-lf1-x12d.google.com [IPv6:2a00:1450:4864:20::12d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1139CC061570; Mon, 8 Nov 2021 03:58:08 -0800 (PST) Received: by mail-lf1-x12d.google.com with SMTP id u11so35619987lfs.1; Mon, 08 Nov 2021 03:58:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=hrYIwuaickwVIX9nv5A/yaHsS4Ix6DSVs2dpM8KjH4o=; b=d1GUMgFByKbIgoH5GKMfZLg18V3Pvs1vpLAjCSW6tR9WEbVeRvjda+OrwVgn55Xvi3 MMN61cx70hV0Hpd+qlq+gQk+get5yUBBISi5bZ9ybBoddoKtfalsgKvU2fKJh951WdGM UV4iLu88mZCur1cXaZHq63eUBedPtx3V2BazJQL2oanX2l0yAqZaLBMMd1Nt9y7p3SUB M0/gyfOqCT9fdnIeTp5l5u8J6bI96Z07CSQyv9j8qKaOMUFGQRwHijNvCphmuRNFUBvl +ZvakDZkdfHEHMmge2V09SnqIkjaXpDqmaDvmPPwNMCoW22FyPkBgCCztpwvttxfP7lI TdLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=hrYIwuaickwVIX9nv5A/yaHsS4Ix6DSVs2dpM8KjH4o=; b=EdEZXwyLB/rc75dI3/1D0zNUtxaP649Q5Io4+u6z/TGNBLhuHjcq5N9iKjCaBzWwTj 9j0tBAG6VfODroSk0QP2B9yL9bX4584NMZhzv1UyzBPsNbTrPRfqx0TGQ31FN3wOvlwG ZyDYC6nQjQJqqPTehTLT3kpng5Abmpd6c9lZCzDGvx8tMQWt/II9lwoHpdHYBzrm15ri cZVF2A4uqQOVseZVrjLOFN6KXHfPWme83zF+9l7bSCj1DON7GwCQmqF8QvCb/K5HJCL8 aS/d3Z6t3WC7b1GWxjlu0vcieXrvLOxTcBMj/xHYA8aVKPj+5bw/1mY9v8lZBEael2iI Gs4Q== X-Gm-Message-State: AOAM532pWFFjA+x5b+ZxKCZMyY9xzynJtbAhm9jHe2fl7KtKVgyFHxSa 4RQBU08R7bdcsHfqprB9CLI= X-Google-Smtp-Source: ABdhPJw+/HXa6QCL/PDO4vo2ym6gJYbrgnqVuNy8PJ3XD9TeQLKLdch4iVk9MaFPGCCXQAOhDsOWGw== X-Received: by 2002:a05:6512:aca:: with SMTP id n10mr8634445lfu.649.1636372686350; Mon, 08 Nov 2021 03:58:06 -0800 (PST) Received: from [192.168.1.11] ([94.103.224.112]) by smtp.gmail.com with ESMTPSA id u12sm1148267lff.271.2021.11.08.03.58.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 08 Nov 2021 03:58:05 -0800 (PST) Message-ID: <9e3047a9-ad29-ab83-670b-4d28e6ec6dbf@gmail.com> Date: Mon, 8 Nov 2021 14:58:04 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.1 Subject: Re: [PATCH] tty: vt: keyboard: do not copy an extra-byte in copy_to_user Content-Language: en-US To: Ajay Garg Cc: Andy Shevchenko , Greg KH , jirislaby@kernel.org, kernel@esmil.dk, David Laight , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20211106092041.43745-1-ajaygargnsit@gmail.com> <9eafae1f-d9f0-298d-cf20-212865d0becc@gmail.com> <868025b485b94480ad17d0ec971b3ee9@AcuMS.aculab.com> <6b58a3e1-f2ea-cc4c-03b2-06334b559373@gmail.com> <9717b429-597f-7778-c880-94361bcdee7f@gmail.com> <65c45951-08ba-26bb-f96b-3d4442b1d4d4@gmail.com> From: Pavel Skripkin In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On 11/8/21 11:59, Ajay Garg wrote: > Dropping all further discussions on this thread, as a RFC for a new > string-copy method has been posted at : > https://lore.kernel.org/linux-hardening/CAHP4M8U=0aTHgfREGJpSboV6J4X+E3Y6+H_kb-PvXxDKtV=n-g@mail.gmail.com/T/#t > > which, if accepted, will make the clients' lives a lot easier. > Honestly, I can't get what you are trying to achieve with new string function. If caller knows, that there is no possible overflow, it can omit bounds checking (like in vt_do_kdgkb_ioctl). If caller needs return value equal to destination length it can use strscpy(). There is a bunch of str*cpy() functions and every month I see new conversations between them on ML. As Andy said it's really chaos. These conversation are needed, of course, from security point of view, but lib/string is already big. It contains functions for every possible scenario, caller just needs to pick right one. I might be too dumb in this topic, so it's just my IMHO, since I am on CC list. With regards, Pavel Skripkin