[PATCH] drviers/md: fix max dup length for kstrndup

[Ma Shimiao]

If source string longer than max, kstrndup will alloc max+1 space.
So, we should make sure the result will not over limit.

Signed-off-by: Ma Shimiao <mashimiao.f...@cn.fujitsu.com>
---
 drivers/md/dm-log-writes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 189badbeddaf..3362d866793b 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -594,7 +594,7 @@ static int log_mark(struct log_writes_c *lc, char *data)
                return -ENOMEM;
        }
 
-       block->data = kstrndup(data, maxsize, GFP_KERNEL);
+       block->data = kstrndup(data, maxsize - 1, GFP_KERNEL);
        if (!block->data) {
                DMERR("Error copying mark data");
                kfree(block);
-- 
2.13.6