RE: [PATCH net-next 1/1] hv_netvsc: Check status in SEND_RNDIS_PKT completion message

[Haiyang Zhang]

> -----Original Message-----
> From: Michael Kelley (LINUX) <mikelley@xxxxxxxxxxxxx>
> Sent: Wednesday, February 8, 2023 6:50 PM
> To: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxx>; wei.liu@xxxxxxxxxx; Dexuan Cui
> <decui@xxxxxxxxxxxxx>; davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx;
> kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> hyperv@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: Michael Kelley (LINUX) <mikelley@xxxxxxxxxxxxx>
> Subject: [PATCH net-next 1/1] hv_netvsc: Check status in SEND_RNDIS_PKT
> completion message
> 
> Completion responses to SEND_RNDIS_PKT messages are currently processed
> regardless of the status in the response, so that resources associated
> with the request are freed.  While this is appropriate, code bugs that
> cause sending a malformed message, or errors on the Hyper-V host, go
> undetected. Fix this by checking the status and outputting a message
> if there is an error.
> 
> Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> ---
>  drivers/net/hyperv/netvsc.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index 661bbe6..caf22e9 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -813,6 +813,7 @@ static void netvsc_send_completion(struct net_device
> *ndev,
>  	u32 msglen = hv_pkt_datalen(desc);
>  	struct nvsp_message *pkt_rqst;
>  	u64 cmd_rqst;
> +	u32 status;
> 
>  	/* First check if this is a VMBUS completion without data payload */
>  	if (!msglen) {
> @@ -884,6 +885,22 @@ static void netvsc_send_completion(struct
> net_device *ndev,
>  		break;
> 
>  	case NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE:
> +		if (msglen < sizeof(struct nvsp_message_header) +
> +		    sizeof(struct
> nvsp_1_message_send_rndis_packet_complete)) {
> +			netdev_err(ndev, "nvsp_rndis_pkt_complete length
> too small: %u\n",
> +				   msglen);
> +			return;
> +		}
> +
> +		/* If status indicates an error, output a message so we know
> +		 * there's a problem. But process the completion anyway so
> the
> +		 * resources are released.
> +		 */
> +		status = nvsp_packet-
> >msg.v1_msg.send_rndis_pkt_complete.status;
> +		if (status != NVSP_STAT_SUCCESS)
> +			netdev_err(ndev, "nvsp_rndis_pkt_complete error
> status: %x\n",
> +				   status);
> +

Could you add rate limit to this error, so in case it happens frequently, the 
errors won't fill up the dmesg.

Or even better, add a counter for this.

Thanks,
- Haiyang