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

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@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
CC: stable@vger.kernel.org  # v3.15+

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 423cb9f8ab0dc216efc14bd440abea8acaf158d6..3b11d23c6749faa3eb70f415ee6f77961797340e 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1997,7 +1997,7 @@ 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;