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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 D35CCC433E2 for ; Mon, 7 Sep 2020 10:30:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85AF92067C for ; Mon, 7 Sep 2020 10:30:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=baylibre-com.20150623.gappssmtp.com header.i=@baylibre-com.20150623.gappssmtp.com header.b="YKpxYuJt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728841AbgIGK3h (ORCPT ); Mon, 7 Sep 2020 06:29:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728950AbgIGK2T (ORCPT ); Mon, 7 Sep 2020 06:28:19 -0400 Received: from mail-ej1-x644.google.com (mail-ej1-x644.google.com [IPv6:2a00:1450:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4AD64C0613ED for ; Mon, 7 Sep 2020 03:28:17 -0700 (PDT) Received: by mail-ej1-x644.google.com with SMTP id o8so4359034ejb.10 for ; Mon, 07 Sep 2020 03:28:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=E+6kvSO+kGtFqzwSOsHYLQdHmE8ihK39UIVQKLTGAlE=; b=YKpxYuJtNjDEcMyhlLGRj0HX0hQkUXEqPjKuUoBXv/e3UDUS4Hln7rKvyvdJTkScwl k1rXYkIZAbO2UsMaPTxTaUrbbBWUu4R8sdHC0L1BG0mGaX4xk380OjSevy0ECUxykK/F W0r2qxkPzqjPoDdZ8gzABSBUnDIUQFXvKxYS4mab97WFlQCFfhbvkd4IVjnPhoWyKel2 XD9I7vu5rWTXsRIKY4qpSRmj1lEfs+bqL5eIbLSlZkr5OCsU1EbDHMwj00krDCJyqj4O gmJBrn/Lyg7t/40d/iHFqrkkALM3z3AbVL2yVDPRt/STFncNY1w/mvM9VKLyly28uSNr Y8vQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=E+6kvSO+kGtFqzwSOsHYLQdHmE8ihK39UIVQKLTGAlE=; b=rEa4CTHUHlC0yZXCBtfqk3DBRM96laQ0iM6M5gbFx5nM9T7a81hPNk7hQmAHQ/GNMY vIrxQN86SDYaWMTLjsniRMi/0yljNWtRGmxupDWTh7SnFqNSkAEU3Qhvtd62apcTo8W+ 9jaUTvXZ7eetoDT3q5zATf7SVEk0G22+rqDBmd1YrQz0+u7l9FQjxNvuHytFntOH4yTu 070vRRkJkP1TZIHPpcxvBawvVBTB7kRfx+Ys+VNucTBMylVWCc5rGExhNPthI5LiuBVi Z03PvqLvI0Jkatzvum7HOGW84uj7X0GYfUWE3gwVYUhakYC4tuZuRUPHEQyAhLle+7L7 AHkg== X-Gm-Message-State: AOAM533O4kUxQmkeVmuKOrQPseKXCo8lHArzDhZj3eY9BcW67wzOYVd5 Losg3MbArq2XQBSVhqYJ7LZi8omtkh6DPCjX5W4veQ== X-Google-Smtp-Source: ABdhPJwP4J3kM7zvzHGchdWRMUs1XHCPsNoozGebnZDrc/LmkHpUC8eNrTX90FFgDqlq6JBHy5dgtK4984ghibSDrvg= X-Received: by 2002:a17:906:941a:: with SMTP id q26mr20103973ejx.496.1599474496010; Mon, 07 Sep 2020 03:28:16 -0700 (PDT) MIME-Version: 1.0 References: <20200904154547.3836-1-brgl@bgdev.pl> <20200904154547.3836-4-brgl@bgdev.pl> <20200904163517.GW1891694@smile.fi.intel.com> In-Reply-To: From: Bartosz Golaszewski Date: Mon, 7 Sep 2020 12:28:05 +0200 Message-ID: Subject: Re: [PATCH 03/23] lib: uaccess: provide getline_from_user() To: Andy Shevchenko Cc: Andy Shevchenko , Bartosz Golaszewski , Linus Walleij , Jonathan Corbet , Mika Westerberg , Kent Gibson , linux-gpio , linux-doc , LKML , ACPI Devel Maling List Content-Type: text/plain; charset="UTF-8" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Mon, Sep 7, 2020 at 12:19 PM Andy Shevchenko wrote: > > On Mon, Sep 7, 2020 at 1:05 PM Bartosz Golaszewski > wrote: > > On Fri, Sep 4, 2020 at 6:35 PM Andy Shevchenko > > wrote: > > > On Fri, Sep 04, 2020 at 05:45:27PM +0200, Bartosz Golaszewski wrote: > > > > From: Bartosz Golaszewski > > > > Doesn't mm/util.c provides us something like this? > > > strndup_user()? > > > > > > > Yes, there's both strndup_user() as well as strncpy_from_user(). The > > problem is that they rely on the strings being NULL-terminated. This > > is not guaranteed for debugfs file_operations write callbacks. We need > > some helper that takes the minimum of bytes provided by userspace and > > the buffer size and figure out how many bytes to actually copy IMO. > > Wouldn't this [1] approach work? > > [1]: https://elixir.bootlin.com/linux/v5.9-rc3/source/arch/x86/kernel/cpu/mtrr/if.c#L93 > Sure, but this is pretty much what I do in getline_from_user(). If anything we should port mtrr_write() to using getline_from_user() once it's available upstream, no? Bart