linux-kernel - [PATCH] iommu/vt-d: fix memory leakage caused by commit ea8ea46

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Date:	Wed,  9 Apr 2014 10:20:39 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	David Woodhouse <David.Woodhouse@...el.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Joerg Roedel <joro@...tes.org>
Cc:	Jiang Liu <jiang.liu@...ux.intel.com>,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH] iommu/vt-d: fix memory leakage caused by commit ea8ea46

Commit ea8ea46 "iommu/vt-d: Clean up and fix page table clear/free
behaviour" introduces possible leakage of DMA page tables due to:
        for (pte = page_address(pg); !first_pte_in_page(pte); pte++) {
                if (dma_pte_present(pte) && !dma_pte_superpage(pte))
                        freelist = dma_pte_list_pagetables(domain, level - 1,
                                                           pte, freelist);
        }

For the first pte in a page, first_pte_in_page(pte) will always be true,
thus dma_pte_list_pagetables() will never be called and leak DMA page
tables if level is bigger than 1.

Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
---
 drivers/iommu/intel-iommu.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 69fa7da..13dc231 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1009,11 +1009,13 @@ static struct page *dma_pte_list_pagetables(struct dmar_domain *domain,
 	if (level == 1)
 		return freelist;
 
-	for (pte = page_address(pg); !first_pte_in_page(pte); pte++) {
+	pte = page_address(pg);
+	do {
 		if (dma_pte_present(pte) && !dma_pte_superpage(pte))
 			freelist = dma_pte_list_pagetables(domain, level - 1,
 							   pte, freelist);
-	}
+		pte++;
+	} while (!first_pte_in_page(pte));
 
 	return freelist;
 }
-- 
1.7.10.4

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