[PATCH 3.16.y-ckt 056/118] ARM: 8404/1: dma-mapping: fix off-by-one error in bitmap size check

From: Luis Henriques
Date: Wed Aug 12 2015 - 05:29:05 EST

3.16.7-ckt16 -stable review patch. If anyone has any objections, please let me know.


From: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

commit 462859aa7bbe1ac83ec4377a0a06fe60778f3f27 upstream.

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@xxxxxxxxxxx>
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Reviewed-by: Hyungwon Hwang <human.hwang@xxxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
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 1f88db06b133..0e09af35f69a 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2013,7 +2013,7 @@ 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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