From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754592AbbALSTW (ORCPT ); Mon, 12 Jan 2015 13:19:22 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:57607 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753613AbbALSGP (ORCPT ); Mon, 12 Jan 2015 13:06:15 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Jiang Liu , Joerg Roedel , Luis Henriques Subject: [PATCH 3.16.y-ckt 068/216] iommu/vt-d: Fix an off-by-one bug in __domain_mapping() Date: Mon, 12 Jan 2015 18:03:05 +0000 Message-Id: <1421085933-32536-69-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> References: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiang Liu commit cc4f14aa170d895c9a43bdb56f62070c8a6da908 upstream. There's an off-by-one bug in function __domain_mapping(), which may trigger the BUG_ON(nr_pages < lvl_pages) when (nr_pages + 1) & superpage_mask == 0 The issue was introduced by commit 9051aa0268dc "intel-iommu: Combine domain_pfn_mapping() and domain_sg_mapping()", which sets sg_res to "nr_pages + 1" to avoid some of the 'sg_res==0' code paths. It's safe to remove extra "+1" because sg_res is only used to calculate page size now. Reported-And-Tested-by: Sudeep Dutt Signed-off-by: Jiang Liu Acked-By: David Woodhouse Signed-off-by: Joerg Roedel [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques --- drivers/iommu/intel-iommu.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 382c1801a8f1..b36bd2886940 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -1966,7 +1966,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn, struct dma_pte *first_pte = NULL, *pte = NULL; phys_addr_t uninitialized_var(pteval); int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT; - unsigned long sg_res; + unsigned long sg_res = 0; unsigned int largepage_lvl = 0; unsigned long lvl_pages = 0; @@ -1977,10 +1977,8 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn, prot &= DMA_PTE_READ | DMA_PTE_WRITE | DMA_PTE_SNP; - if (sg) - sg_res = 0; - else { - sg_res = nr_pages + 1; + if (!sg) { + sg_res = nr_pages; pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | prot; } -- 2.1.4