[PATCH] arm: dma-mapping: fix off-by-one error in bitmap size check

Marek Szyprowski m.szyprowski at samsung.com
Wed Jul 1 05:48:03 PDT 2015

nr_bitmaps member of mapping structure stores the number of already
allocated bitmaps and it is interpreted as loop iterator (it starts from
0 not from 1), so a comparison against number of possible bitmap
extensions should include this fact. This patch fixes this by changing
the extension failure condition. This issue has been introduced by
commit 4d852ef8c2544ce21ae41414099a7504c61164a0 ("arm: dma-mapping: Add
support to extend DMA IOMMU mappings").

Reported-by: Hyungwon Hwang <human.hwang at samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
CC: stable at vger.kernel.org  # v3.15+
 arch/arm/mm/dma-mapping.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index a64b7f621067..05619542a1c0 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2015,7 +2015,7 @@ static int extend_iommu_mapping(struct dma_iommu_mapping *mapping)
 	int next_bitmap;
-	if (mapping->nr_bitmaps > mapping->extensions)
+	if (mapping->nr_bitmaps => mapping->extensions)
 		return -EINVAL;
 	next_bitmap = mapping->nr_bitmaps;

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