[PATCH] vmbus: don't return values for uninitalized channels

[PATCH] vmbus: don't return values for uninitalized channels

[kys]

From: Stephen Hemminger <stephen@networkplumber.org>

For unsupported device types, the vmbus channel ringbuffer is never
initialized, and therefore reading the sysfs files will return garbage
or cause a kernel OOPS.

Fixes: c2e5df616e1a ("vmbus: add per-channel sysfs info")

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org> # 4.15
---
 drivers/hv/vmbus_drv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index e6d8fdac6d8b..4bbc420d1213 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1368,6 +1368,9 @@ static ssize_t vmbus_chan_attr_show(struct kobject *kobj,
 	if (!attribute->show)
 		return -EIO;
 
+	if (chan->state != CHANNEL_OPENED_STATE)
+		return -EINVAL;
+
 	return attribute->show(chan, buf);
 }
 
-- 
2.18.0

Re: [PATCH] vmbus: don't return values for uninitalized channels

[Vitaly Kuznetsov]

kys@linuxonhyperv.com writes:

> From: Stephen Hemminger <stephen@networkplumber.org>
>
> For unsupported device types, the vmbus channel ringbuffer is never
> initialized, and therefore reading the sysfs files will return garbage
> or cause a kernel OOPS.
>
> Fixes: c2e5df616e1a ("vmbus: add per-channel sysfs info")
>
> Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> Cc: <stable@vger.kernel.org> # 4.15

As this is also marked for stable, any chance we can get it in 4.19? Or
at least in char-misc-next?

> ---
>  drivers/hv/vmbus_drv.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index e6d8fdac6d8b..4bbc420d1213 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -1368,6 +1368,9 @@ static ssize_t vmbus_chan_attr_show(struct kobject *kobj,
>  	if (!attribute->show)
>  		return -EIO;
>
> +	if (chan->state != CHANNEL_OPENED_STATE)
> +		return -EINVAL;
> +
>  	return attribute->show(chan, buf);
>  }

Thanks,

-- 
  Vitaly