[PATCH 1/3] zram: fix operator precedence to get offset

Minchan Kim
2017-04-13T00:17:17Z

In zram_rw_page, the logic to get offset is wrong by operator precedence
(i.e., "<<" is higher than "&"). With wrong offset, zram can corrupt the
user's data. This patch fixes it.

Fixes: 8c7f01025 ("zram: implement rw_page operation of zram")
Cc: stable@vger.kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
drivers/block/zram/zram_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9e2199060040..83c38a123242 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -930,7 +930,7 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
}

index = sector >> SECTORS_PER_PAGE_SHIFT;
- offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT;
+ offset = (sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;

bv.bv_page = page;
bv.bv_len = PAGE_SIZE;
--
2.7.4