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=-12.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 29F75C433DF for ; Thu, 20 Aug 2020 23:20:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE2E0206B5 for ; Thu, 20 Aug 2020 23:20:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hoOgqZhG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728805AbgHTXUt (ORCPT ); Thu, 20 Aug 2020 19:20:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44492 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728600AbgHTXUr (ORCPT ); Thu, 20 Aug 2020 19:20:47 -0400 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62031C061385; Thu, 20 Aug 2020 16:20:47 -0700 (PDT) Received: by mail-pl1-x644.google.com with SMTP id g15so26313plj.6; Thu, 20 Aug 2020 16:20:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=UkH8Mq/WpiesfkXrapLTRLCROpdsRyoJty+98OOSpss=; b=hoOgqZhGHiVLpZeCypo4yuc1a8zxVmMSd4yoH7tyVhF3yOb7NtMj1zSNv5XfOuI8DT AlWGPfC0Tt9WPeOHXgkAJrJ/ujCTJum25ZaPdnCViQhCDmL0ejq62ZpTP2MGf4xcxoG8 //dWA4yoVM2FcKhy57jS98tWjNVY/WXBREVn+qyRrzr0dNU9BFecxR1XvgAZn8URED5w +wPjTvUxEMZMZxwJorp0FAVs6Dzx3oks+bUOWlOL32lAOOxtFLtLFbeFQ7+BB6ZrSXwE 1dNhIXaStLdULE8UgwJGkL+NBxfVbloj5Xsb4QHOV2z6TzlIER2wWcUh9flW3IGobrpm XDxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=UkH8Mq/WpiesfkXrapLTRLCROpdsRyoJty+98OOSpss=; b=VfzOpAUGCub3lAiIZ5YKZdKAWNV05Y2N8OuKnUgfP4btaJT8iEFY3dt8shIlSz03ft R1fCGpsckPZ/UwyPl1gzsEWCoafKa3uJCBaMQh0/5BOZNRn1WyNiHkBgdByRYImAJvix G9WI5evU/FVLx/FsECZz77aS+pXka9SwqdU0yqiHHQv4mwsNwjYHA3si5GOSFKobhXvd H3AG5CDCAXJJeVufKNgJ64W52HxzznVSVQraC+6+hb2Xx+mL3aYkbNaIfoumWjQHlAax zRO1LXG/hM8Uw/VSdha2itdajHCqNyDWZyHlMqmtITk6vHPOsuvvTdL1KYPXVp5f5Cr0 L4Wg== X-Gm-Message-State: AOAM530DznaMRkTOLg1iCszwYwNjc/g/S4Nb84TSf3Ee0yCGHluCHO7U w9zNk5kr2vSPsznoHXrPm+rp94TNC3sQ3Q== X-Google-Smtp-Source: ABdhPJy6feg2kk7nTvSUH+AHBQAq+ZwdrDgcKqcb43pyrkAEQJqGzIlQH6xWUZuZ1neelwbWE1oCvA== X-Received: by 2002:a17:90b:255:: with SMTP id fz21mr202213pjb.50.1597965646928; Thu, 20 Aug 2020 16:20:46 -0700 (PDT) Received: from Asurada-Nvidia.nvidia.com (thunderhill.nvidia.com. [216.228.112.22]) by smtp.gmail.com with ESMTPSA id b15sm112786pgk.14.2020.08.20.16.20.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Aug 2020 16:20:46 -0700 (PDT) From: Nicolin Chen To: schnelle@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com Cc: hch@lst.de, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFT][PATCH 4/7] s390/pci_dma: Avoid overflow at boundary_size Date: Thu, 20 Aug 2020 16:20:32 -0700 Message-Id: <20200820232032.23846-1-nicoleotsuka@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The boundary_size might be as large as ULONG_MAX, which means that a device has no specific boundary limit. So either "+ 1" or passing it to ALIGN() would potentially overflow. According to kernel defines: #define ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask)) #define ALIGN(x, a) ALIGN_MASK(x, (typeof(x))(a) - 1) We can simplify the logic here: ALIGN(boundary + 1, 1 << shift) >> shift = ALIGN_MASK(b + 1, (1 << s) - 1) >> s = {[b + 1 + (1 << s) - 1] & ~[(1 << s) - 1]} >> s = [b + 1 + (1 << s) - 1] >> s = [b + (1 << s)] >> s = (b >> s) + 1 So fixing a potential overflow with the safer shortcut. Signed-off-by: Nicolin Chen Cc: Christoph Hellwig --- arch/s390/pci/pci_dma.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c index 64b1399a73f0..ecb067acc6d5 100644 --- a/arch/s390/pci/pci_dma.c +++ b/arch/s390/pci/pci_dma.c @@ -263,8 +263,8 @@ static unsigned long __dma_alloc_iommu(struct device *dev, struct zpci_dev *zdev = to_zpci(to_pci_dev(dev)); unsigned long boundary_size; - boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1, - PAGE_SIZE) >> PAGE_SHIFT; + /* Overflow-free shortcut for: ALIGN(b + 1, 1 << s) >> s */ + boundary_size = (dma_get_seg_boundary(dev) >> PAGE_SHIFT) + 1; return iommu_area_alloc(zdev->iommu_bitmap, zdev->iommu_pages, start, size, zdev->start_dma >> PAGE_SHIFT, boundary_size, 0); -- 2.17.1