linux-kernel - [PATCH] iommu/amd: Handle integer overflow in dma_ops_area

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Message-Id: <1432711569-18890-1-git-send-email-joro@8bytes.org>
Date:	Wed, 27 May 2015 09:26:09 +0200
From:	Joerg Roedel <joro@...tes.org>
To:	iommu@...ts.linux-foundation.org
Cc:	linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>
Subject: [PATCH] iommu/amd: Handle integer overflow in dma_ops_area_alloc

From: Joerg Roedel <jroedel@...e.de>

Handle this case to make sure boundary_size does not become
0 and trigger a BUG_ON later.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 drivers/iommu/amd_iommu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index e43d489..f2d12c0 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1704,14 +1704,16 @@ static unsigned long dma_ops_area_alloc(struct device *dev,
 	unsigned long next_bit = dom->next_address % APERTURE_RANGE_SIZE;
 	int max_index = dom->aperture_size >> APERTURE_RANGE_SHIFT;
 	int i = start >> APERTURE_RANGE_SHIFT;
-	unsigned long boundary_size;
+	unsigned long boundary_size, mask;
 	unsigned long address = -1;
 	unsigned long limit;
 
 	next_bit >>= PAGE_SHIFT;
 
-	boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
-			PAGE_SIZE) >> PAGE_SHIFT;
+	mask = dma_get_seg_boundary(dev);
+
+	boundary_size = mask + 1 ? ALIGN(mask + 1, PAGE_SIZE) >> PAGE_SHIFT :
+				   1UL << (BITS_PER_LONG - PAGE_SHIFT);
 
 	for (;i < max_index; ++i) {
 		unsigned long offset = dom->aperture[i]->offset >> PAGE_SHIFT;
-- 
1.9.1

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