[PATCH 4.1 010/123] ARM: 8404/1: dma-mapping: fix off-by-one error in bitmap size check

From: Greg Kroah-Hartman
Date: Sat Aug 08 2015 - 18:38:46 EST

4.1-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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/arm/mm/dma-mapping.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1953,7 +1953,7 @@ static int extend_iommu_mapping(struct d
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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