From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762093AbbA2JtA (ORCPT ); Thu, 29 Jan 2015 04:49:00 -0500 Received: from ip4-83-240-67-251.cust.nbox.cz ([83.240.67.251]:44816 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752358AbbA2JER (ORCPT ); Thu, 29 Jan 2015 04:04:17 -0500 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jiang Liu , Joerg Roedel , Jiri Slaby Subject: [PATCH 3.12 019/176] iommu/vt-d: Fix an off-by-one bug in __domain_mapping() Date: Wed, 28 Jan 2015 15:27:29 +0100 Message-Id: X-Mailer: git-send-email 2.2.2 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jiang Liu 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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 Signed-off-by: Jiri Slaby --- 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 911ecb230b5a..fd0516c9fbfe 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -1796,7 +1796,7 @@ 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; @@ -1807,10 +1807,8 @@ 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; } -- 2.2.2