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=-2.7 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, 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 6C1ABC433E0 for ; Thu, 11 Feb 2021 09:56:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A2AC64E8A for ; Thu, 11 Feb 2021 09:56:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229752AbhBKJ4a (ORCPT ); Thu, 11 Feb 2021 04:56:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229971AbhBKJyV (ORCPT ); Thu, 11 Feb 2021 04:54:21 -0500 Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59707C061756; Thu, 11 Feb 2021 01:53:41 -0800 (PST) Received: by mail-pj1-x102f.google.com with SMTP id fa16so3093906pjb.1; Thu, 11 Feb 2021 01:53:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/2/r886KQW4/hmgGlGU/bFt+5s/atopbbN5Yr8MK8T8=; b=vQystuV8OWeUPFQ3fFsiGIqaSCxcNFDVbhkLn8xcohJXWQYYbiqtdKXbckM/D9dXCj fKfz2kijNBYFNr1/O3rZVTte5r+2gb9FoXlFVJ18L1BEtiy1mj0aydeUAFMbUdY+fL3t v56Qrbz5YTHi3tcxlPE6C3GmKyjzFV/l1B8uDD4k8gT4/oXpV4Q+BeLY8RxxionPZtaF JaTGGQFKDYAxh6gZXVQAN+orJ5fbL/1iykRtYV3EueJ0ryiyxDOA4T6mEF/bgvP28BQL hqtTEfVqaVaCV7S/ISIF+VVf6afLIpQwNZADARhn53ecri4gZOZZOhQzsAjCpIiqBmyW 6KjA== 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=/2/r886KQW4/hmgGlGU/bFt+5s/atopbbN5Yr8MK8T8=; b=Aq9eBqAMHcRJ6elRm2ttzu2/U12F1YSeXwhL9h/x1cyXVOg4YDOhDfmaBSzuVeoBnf ekQV1LLmxWHuV4j/zZWFSBTBhu1OkZF8eDtulAQJrMfa8EEeZ26XclqxRCvv503PkAWQ 4fZ0U2r7wdBIE62xzMKH+PIyG+655311OihUAwGHi8XgCySck3nNh1puET36rH1buIHO GyslQwa5UlExzA0blxfnD92b2BjgS65RCd45kPOsHpOLbR6ipdTUFnetg7sRcIRoKwtw a3wSDw5IsHifnHzH37GdZfg+q4jVtqAIbODtHv8zHk6tQfTGNBM0zI9m2UASnINbV7tt RFbg== X-Gm-Message-State: AOAM5316mF4AovNAANe/S4xnFYqF6sNkyNJPjjX3cjmYxJSChAwUCRTx q7x5t8wCD644/K3Y8Eo4zF5CNQPpReTAE/G9wJ0= X-Google-Smtp-Source: ABdhPJy+YBCILgGQR6FWOWTfpw13kwHqTUdrByKLx3NGo6g9JeyKlKtrYRmpysTlLijpT38oXfcXSyWU5WPSPL2KbwE= X-Received: by 2002:a17:902:be14:b029:e1:bec9:f4a7 with SMTP id r20-20020a170902be14b02900e1bec9f4a7mr7208681pls.21.1613037220776; Thu, 11 Feb 2021 01:53:40 -0800 (PST) MIME-Version: 1.0 References: <20210210222851.232374-1-drew@beagleboard.org> <20210210222851.232374-3-drew@beagleboard.org> In-Reply-To: From: Andy Shevchenko Date: Thu, 11 Feb 2021 11:53:24 +0200 Message-ID: Subject: Re: [PATCH v4 2/2] pinctrl: pinmux: Add pinmux-select debugfs file To: Geert Uytterhoeven Cc: Drew Fustini , Linus Walleij , "open list:GPIO SUBSYSTEM" , Linux Kernel Mailing List , Tony Lindgren , Alexandre Belloni , Pantelis Antoniou , Jason Kridner , Robert Nelson , Joe Perches , Dan Carpenter Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Thu, Feb 11, 2021 at 10:09 AM Geert Uytterhoeven wrote: > On Wed, Feb 10, 2021 at 11:33 PM Drew Fustini wrote: > > +#define PINMUX_MAX_NAME 64 > > + if (len > (PINMUX_MAX_NAME * 2)) { > > + dev_err(pctldev->dev, "write too big for buffer"); > > + return -EINVAL; > > + } > > + > > + buf = kzalloc(PINMUX_MAX_NAME * 2, GFP_KERNEL); > > + ret = strncpy_from_user(buf, user_buf, PINMUX_MAX_NAME * 2); > > While this guarantees buf is not overflowed... > > > + if (ret < 0) { > > + dev_err(pctldev->dev, "failed to copy buffer from userspace"); > > + goto free_gname; > > + } > > + buf[len-1] = '\0'; > > + > > + ret = sscanf(buf, "%s %s", fname, gname); > > ... one of the two strings can still be longer than PINMUX_MAX_NAME, > thus overflowing fname or gname. > > As buf is already a copy, it may be easier to just find the strings in > buf, write the NUL terminators into buf, and set up fname and gname > to point to the strings inside buf. You beat me up to it. I was about to comment the same. So, indeed, instead of sscanf it's simply better and faster to do just something like fname = strstrip(buf) ; if (*fname == '\0') { ... return -EINVAL; } gname = strchr(fname, ' '); if (!gname) { ... return -EINVAL; } *gname++ = '\0'; on top of the buf pointer. > > + if (ret != 2) { > > + dev_err(pctldev->dev, "expected format: "); > > + goto free_gname; > > + } -- With Best Regards, Andy Shevchenko