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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 9EB56C433E2 for ; Wed, 16 Sep 2020 17:34:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 34B72222E7 for ; Wed, 16 Sep 2020 17:34:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="Toq2quLW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727192AbgIPReW (ORCPT ); Wed, 16 Sep 2020 13:34:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727114AbgIPRdp (ORCPT ); Wed, 16 Sep 2020 13:33:45 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79466C035433; Wed, 16 Sep 2020 10:01:01 -0700 (PDT) Received: from zn.tnic (p200300ec2f0c3e00db2f62bd592f04a0.dip0.t-ipconnect.de [IPv6:2003:ec:2f0c:3e00:db2f:62bd:592f:4a0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 153991EC0380; Wed, 16 Sep 2020 19:01:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1600275660; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=LkvwYUOfny5INeLJrbeKgLZhTjk6a4VOIrstYBGgPu4=; b=Toq2quLW5TpQcsGP5DrMm+RsrcWMdI9imdYdNvge5DpZB18SQP3QeRLa/Pgzi6qUdI5RB5 5TAbcTwPjU0bIBRXPQGE+I9R7CbhbgrJscGlti7j70pjvYe86MEVI5cjJnNRTubDd5i60D jae3m9HuKdzGOk24rLnTScrSvac4WWw= Date: Wed, 16 Sep 2020 19:00:52 +0200 From: Borislav Petkov To: Xiongfeng Wang Cc: mchehab@kernel.org, tony.luck@intel.com, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] EDAC/mc_sysfs: Add missing newlines when printing {max,dimm}_location Message-ID: <20200916170052.GO2643@zn.tnic> References: <1600051734-8993-1-git-send-email-wangxiongfeng2@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1600051734-8993-1-git-send-email-wangxiongfeng2@huawei.com> Sender: linux-edac-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org On Mon, Sep 14, 2020 at 10:48:54AM +0800, Xiongfeng Wang wrote: > @@ -813,15 +817,21 @@ static ssize_t mci_max_location_show(struct device *dev, > char *data) > { > struct mem_ctl_info *mci = to_mci(dev); > - int i; > + int i, n; > char *p = data; > + unsigned int len = PAGE_SIZE; > > for (i = 0; i < mci->n_layers; i++) { > - p += sprintf(p, "%s %d ", > + n = snprintf(p, len, "%s %d ", > edac_layer_name[mci->layers[i].type], > mci->layers[i].size - 1); > + p += n; > + len -= n; What happens if that subtraction causes len to wrap around and become a huge positive unsigned integer? > + if (!len) Would that test still work? IOW, I did this to your patch ontop. Note that I've moved the "p" pointer incrementation after the length check so that the pointer doesn't overflow too: --- diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c index bf0e075fb635..fa0551c81e63 100644 --- a/drivers/edac/edac_mc_sysfs.c +++ b/drivers/edac/edac_mc_sysfs.c @@ -817,19 +817,22 @@ static ssize_t mci_max_location_show(struct device *dev, char *data) { struct mem_ctl_info *mci = to_mci(dev); - int i, n; + int len = PAGE_SIZE; char *p = data; - unsigned int len = PAGE_SIZE; + int i, n; for (i = 0; i < mci->n_layers; i++) { n = snprintf(p, len, "%s %d ", edac_layer_name[mci->layers[i].type], mci->layers[i].size - 1); - p += n; + len -= n; - if (!len) + if (len < 0) goto out; + + p += n; } + p += snprintf(p, len, "\n"); out: return p - data; -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette