Commit cf8190e4 authored Dec 10, 2015 by Haiyang Zhang Committed by David S. Miller Dec 14, 2015

hv_netvsc: Fix race condition on Multi-Send Data field



In commit 2a04ae8a ("hv_netvsc: remove locking in netvsc_send()"), the
locking for MSD (Multi-Send Data) field was removed. This could cause a
race condition between RNDIS control messages and data packets processing,
because these two types of traffic are not synchronized.
This patch fixes this issue by sending control messages out directly
without reading MSD field.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent abe492b4

drivers/net/hyperv/netvsc.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -867,6 +867,14 @@ int netvsc_send(struct hv_device *device,
		packet->send_buf_index = NETVSC_INVALID_INDEX;
		packet->cp_partial = false;

		/* Send control message directly without accessing msd (Multi-Send
		* Data) field which may be changed during data packet processing.
		*/
		if (!skb) {
		cur_send = packet;
		goto send_now;
		}

		msdp = &net_device->msd[q_idx];

		/* batch packets in send buffer if possible */
		@@ -939,6 +947,7 @@ int netvsc_send(struct hv_device *device,
		}
		}

		send_now:
		if (cur_send)
		ret = netvsc_send_pkt(cur_send, net_device, pb, skb);