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.d...@intel.com>
Signed-off-by: Jiang Liu <jiang....@linux.intel.com>
Cc: <sta...@vger.kernel.org> # 3.1
---
Hi David and Joerg,
This issue was introduced in v2.6.31, but intel-iommu.c has
been moved into drivers/iommu in v3.1. So what's the preferred way
to deal with stable kernels between v2.6.31 and v3.1?
Thanks!
Gerry
---
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 a27d6cb1a793..b26ad10ec697 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1983,7 +1983,7 @@ 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;
@@ -1994,10 +1994,8 @@ 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;
}
--
1.7.10.4
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