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| author | David Woodhouse <David.Woodhouse@intel.com> | 2009-09-19 07:36:28 -0700 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2009-09-19 07:36:28 -0700 |
| commit | 59c36286b74ae6a8adebf6e133a83d7f2e3e6704 (patch) | |
| tree | ad6d608b560dc540330bdcc89e8702ac85993174 /drivers/pci/intel-iommu.c | |
| parent | 2ebe31513fcbe7a781f27002f065b50ae195022f (diff) | |
| download | lwn-59c36286b74ae6a8adebf6e133a83d7f2e3e6704.tar.gz lwn-59c36286b74ae6a8adebf6e133a83d7f2e3e6704.zip | |
intel-iommu: Fix integer overflow in dma_pte_{clear_range,free_pagetable}()
If end_pfn is equal to (unsigned long)-1, then the loop will never end.
Seen on 32-bit kernel, but could have happened on 64-bit too once we get
hardware that supports 64-bit guest addresses.
Change both functions to a 'do {} while' loop with the test at the end,
and check for the PFN having wrapper round to zero.
Reported-by: Benjamin LaHaise <ben.lahaise@neterion.com>
Tested-by: Benjamin LaHaise <ben.lahaise@neterion.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers/pci/intel-iommu.c')
| -rw-r--r-- | drivers/pci/intel-iommu.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index c9272a1fb691..5493c79dde47 100644 --- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -785,9 +785,10 @@ static void dma_pte_clear_range(struct dmar_domain *domain, BUG_ON(addr_width < BITS_PER_LONG && start_pfn >> addr_width); BUG_ON(addr_width < BITS_PER_LONG && last_pfn >> addr_width); + BUG_ON(start_pfn > last_pfn); /* we don't need lock here; nobody else touches the iova range */ - while (start_pfn <= last_pfn) { + do { first_pte = pte = dma_pfn_level_pte(domain, start_pfn, 1); if (!pte) { start_pfn = align_to_level(start_pfn + 1, 2); @@ -801,7 +802,8 @@ static void dma_pte_clear_range(struct dmar_domain *domain, domain_flush_cache(domain, first_pte, (void *)pte - (void *)first_pte); - } + + } while (start_pfn && start_pfn <= last_pfn); } /* free page table pages. last level pte should already be cleared */ @@ -817,6 +819,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain, BUG_ON(addr_width < BITS_PER_LONG && start_pfn >> addr_width); BUG_ON(addr_width < BITS_PER_LONG && last_pfn >> addr_width); + BUG_ON(start_pfn > last_pfn); /* We don't need lock here; nobody else touches the iova range */ level = 2; @@ -827,7 +830,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain, if (tmp + level_size(level) - 1 > last_pfn) return; - while (tmp + level_size(level) - 1 <= last_pfn) { + do { first_pte = pte = dma_pfn_level_pte(domain, tmp, level); if (!pte) { tmp = align_to_level(tmp + 1, level + 1); @@ -846,7 +849,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain, domain_flush_cache(domain, first_pte, (void *)pte - (void *)first_pte); - } + } while (tmp && tmp + level_size(level) - 1 <= last_pfn); level++; } /* free pgd */ |