RE: [PATCH net-next v2 1/1] hv_netvsc: Check status in SEND_RNDIS_PKT completion message

[Michael Kelley (LINUX)]

From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> Sent: Sunday, February 12, 2023 4:03 PM
> 
> > -----Original Message-----
> > From: Michael Kelley (LINUX) <mikelley@xxxxxxxxxxxxx>
> > Sent: Saturday, February 11, 2023 5:41 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 v2 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 rate-limited
> > message if there is an error.
> >
> > Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> > ---
> >
> > Changes in v2:
> > * Add rate-limiting to error messages [Haiyang Zhang]
> >
> >  drivers/net/hyperv/netvsc.c | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> >
> > diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> > index 661bbe6..90f10ac 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 +885,23 @@ 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) &&
> > +		    net_ratelimit()) {
> > +			netdev_err(ndev, "nvsp_rndis_pkt_complete length too small: %u\n",
> > +				   msglen);
> > +			return;
> > +		}
> 
> The net_ratelimit() condition should be for the error print only, not affect
> the "return".

Argh.  :-(   You're right.  Will fix in v3.

Michael