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iommu/vt-d: Fix an off-by-one bug in __domain_mapping() 

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 9051aa0268 "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>
Cc: <stable@vger.kernel.org> # >= 3.0
Acked-By: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Jiang Liu 2014-11-26 09:42:10 +08:00 committed by Joerg Roedel
parent 864b94adfc
commit cc4f14aa17
1 changed files with 3 additions and 5 deletions
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8
drivers/iommu/intel-iommu.c
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@ -1986,7 +1986,7 @@ 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);
unsigned long sg_res;
unsigned long sg_res = 0;
unsigned int largepage_lvl = 0;
unsigned long lvl_pages = 0;
@ -1997,10 +1997,8 @@ 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;
}