[PATCH net-next v3 1/1] hv_netvsc: Check status in SEND_RNDIS_PKT completion message

[Michael Kelley]

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 v3:
* Fix rate-limit logic when msglen is too small [Haiyang Zhang]

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..f702807 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)) {
+			if (net_ratelimit())
+				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 && net_ratelimit())
+			netdev_err(ndev, "nvsp_rndis_pkt_complete error status: %x\n",
+				   status);
+
 		netvsc_send_tx_complete(ndev, net_device, incoming_channel,
 					desc, budget);
 		break;
-- 
1.8.3.1