[PATCH] s390: cio: fix use-after-free in ccw_device_destroy_console

[Qinglang Miao]

put_device calls release function which do kfree() inside.
So following use of sch&cdev would cause use-after-free bugs.

Fix these by simply adjusting the position of put_device.

Fixes: 37db8985b211 ("s390/cio: add basic protected virtualization support")
Reported-by: Hulk Robot <hul...@huawei.com>
Suggested-by: Cornelia Huck <coh...@redhat.com>
Signed-off-by: Qinglang Miao <miaoqingl...@huawei.com>
---
 This patch is indeed a v2 of older one. Considering that the
 patch's name has changed, I think a normal prefix 'PATCH' is
 better.

 drivers/s390/cio/device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index b29fe8d50..33280ca18 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -1664,10 +1664,10 @@ void __init ccw_device_destroy_console(struct 
ccw_device *cdev)
        struct io_subchannel_private *io_priv = to_io_private(sch);
 
        set_io_private(sch, NULL);
-       put_device(&sch->dev);
-       put_device(&cdev->dev);
        dma_free_coherent(&sch->dev, sizeof(*io_priv->dma_area),
                          io_priv->dma_area, io_priv->dma_area_dma);
+       put_device(&sch->dev);
+       put_device(&cdev->dev);
        kfree(io_priv);
 }
 
-- 
2.23.0