| From | 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 |
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From: Jiang Liu <jiang.liu@linux.intel.com>
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 <sudeep.dutt@intel.com> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> Acked-By: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- 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
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