From: Qinglang Miao <miaoqinglang@huawei.com>
Date: Tue, 1 Dec 2020 14:31:50 +0800
Subject: s390/cio: fix use-after-free in ccw_device_destroy_console
Git-commit: 14d4c4fa46eeaa3922e8e1c4aa727eb0a1412804
Patch-mainline: v5.11-rc1
References: git-fixes

Use of sch->dev reference after the put_device() call could trigger
the use-after-free bugs.

Fix this by simply adjusting the position of put_device.

Fixes: 37db8985b211 ("s390/cio: add basic protected virtualization support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Suggested-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
[vneethv@linux.ibm.com: Slight modification in the commit-message]
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/cio/device.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -1704,10 +1704,10 @@ void __init ccw_device_destroy_console(s
 	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);
 }