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    Subject[PATCH 5.4 258/453] s390/cio: fix use-after-free in ccw_device_destroy_console
    Date
    From: Qinglang Miao <miaoqinglang@huawei.com>

    [ Upstream commit 14d4c4fa46eeaa3922e8e1c4aa727eb0a1412804 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 983f9c9e08deb..23e9227e60fd7 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);
    }

    --
    2.27.0


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