From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David Woodhouse" , "Joerg Roedel" , "Jiang Liu" Date: Tue, 17 Feb 2015 01:46:53 +0000 Message-ID: Subject: [PATCH 3.2 047/152] iommu/vt-d: Fix an off-by-one bug in __domain_mapping() In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.2.67-rc1 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 [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- drivers/iommu/intel-iommu.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -1763,7 +1763,7 @@ static int __domain_mapping(struct dmar_ 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; @@ -1774,10 +1774,8 @@ static int __domain_mapping(struct dmar_ 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; }