[PATCH -next] mtd/ftl: Fix uaf in ftl_remove_dev()

[Gaosheng Cui]

del_mtd_blktrans_dev will reclaim the resources of mtd_blktrans_dev,
and call kfree(dev) in blktrans_dev_put to release the memory of
mtd_blktrans_dev, so when ftl_freepart reclaims the memory of other
member pointers of the partition_t, it will trigger the uaf problem,
Fix it by moving ftl_freepart in front of del_mtd_blktrans_dev.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Gaosheng Cui <cuigaosheng1 at huawei.com>
---
 drivers/mtd/ftl.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ftl.c b/drivers/mtd/ftl.c
index 200271bdc7aa..bec56070039d 100644
--- a/drivers/mtd/ftl.c
+++ b/drivers/mtd/ftl.c
@@ -1039,8 +1039,12 @@ static void ftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
 
 static void ftl_remove_dev(struct mtd_blktrans_dev *dev)
 {
+	struct partition_t *partition;
+
+	partition = container_of(dev, struct partition_t, mbd);
+
+	ftl_freepart(partition);
 	del_mtd_blktrans_dev(dev);
-	ftl_freepart((partition_t *)dev);
 }
 
 static struct mtd_blktrans_ops ftl_tr = {
-- 
2.25.1