2020-12-01 06:27:45

by Qinglang Miao

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

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 <[email protected]>
Suggested-by: Cornelia Huck <[email protected]>
Signed-off-by: Qinglang Miao <[email protected]>
---
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

2020-12-01 10:26:53

by Cornelia Huck

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

On Tue, 1 Dec 2020 14:31:50 +0800
Qinglang Miao <[email protected]> wrote:

> 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 <[email protected]>
> Suggested-by: Cornelia Huck <[email protected]>
> Signed-off-by: Qinglang Miao <[email protected]>
> ---
> 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(-)

Reviewed-by: Cornelia Huck <[email protected]>

2020-12-02 09:34:14

by Vineeth Vijayan

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

Thank you.With a very minor modification in the commit-message,

Reviewed-by: Vineeth Vijayan <[email protected]>

I will push this and Vasliy/Heiko will take this up for the next
s390-tree upstream-release.


On 12/1/20 7:31 AM, Qinglang Miao wrote:
> 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.

Modified the commit-message as below. Just for the clarification.

--

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 <[email protected]>
> Suggested-by: Cornelia Huck <[email protected]>
> Signed-off-by: Qinglang Miao <[email protected]>
> ---
> 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);
> }
>