From 59c36286b74ae6a8adebf6e133a83d7f2e3e6704 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Sat, 19 Sep 2009 07:36:28 -0700 Subject: [PATCH] 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 Tested-by: Benjamin LaHaise Signed-off-by: David Woodhouse --- drivers/pci/intel-iommu.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index c9272a1fb69..5493c79dde4 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 */