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>
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@ -785,9 +785,10 @@ static void dma_pte_clear_range(struct dmar_domain *domain,
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BUG_ON(addr_width < BITS_PER_LONG && start_pfn >> addr_width);
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BUG_ON(addr_width < BITS_PER_LONG && last_pfn >> addr_width);
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BUG_ON(start_pfn > last_pfn);
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/* we don't need lock here; nobody else touches the iova range */
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while (start_pfn <= last_pfn) {
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do {
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first_pte = pte = dma_pfn_level_pte(domain, start_pfn, 1);
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if (!pte) {
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start_pfn = align_to_level(start_pfn + 1, 2);
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@ -801,7 +802,8 @@ static void dma_pte_clear_range(struct dmar_domain *domain,
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domain_flush_cache(domain, first_pte,
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(void *)pte - (void *)first_pte);
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}
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} while (start_pfn && start_pfn <= last_pfn);
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}
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/* free page table pages. last level pte should already be cleared */
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@ -817,6 +819,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain,
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BUG_ON(addr_width < BITS_PER_LONG && start_pfn >> addr_width);
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BUG_ON(addr_width < BITS_PER_LONG && last_pfn >> addr_width);
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BUG_ON(start_pfn > last_pfn);
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/* We don't need lock here; nobody else touches the iova range */
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level = 2;
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@ -827,7 +830,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain,
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if (tmp + level_size(level) - 1 > last_pfn)
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return;
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while (tmp + level_size(level) - 1 <= last_pfn) {
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do {
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first_pte = pte = dma_pfn_level_pte(domain, tmp, level);
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if (!pte) {
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tmp = align_to_level(tmp + 1, level + 1);
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@ -846,7 +849,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain,
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domain_flush_cache(domain, first_pte,
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(void *)pte - (void *)first_pte);
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}
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} while (tmp && tmp + level_size(level) - 1 <= last_pfn);
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level++;
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}
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/* free pgd */
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