hyperv: Fix a bug in netvsc_send()

After the packet is successfully sent, we should not touch the packet
as it may have been freed. This patch is based on the work done by
Long Li <longli@microsoft.com>.

David, please queue this up for stable.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 66979cf7fca6..da2d34688370 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -705,6 +705,7 @@ int netvsc_send(struct hv_device *device,
         unsigned int section_index = NETVSC_INVALID_INDEX;
         u32 msg_size = 0;
         struct sk_buff *skb;
+        u16 q_idx = packet->q_idx;
 
 
         net_device = get_outbound_net_device(device);
@@ -769,24 +770,24 @@ int netvsc_send(struct hv_device *device,
 
         if (ret == 0) {
                 atomic_inc(&net_device->num_outstanding_sends);
-                atomic_inc(&net_device->queue_sends[packet->q_idx]);
+                atomic_inc(&net_device->queue_sends[q_idx]);
 
                 if (hv_ringbuf_avail_percent(&out_channel->outbound) <
                         RING_AVAIL_PERCENT_LOWATER) {
                         netif_tx_stop_queue(netdev_get_tx_queue(
-                                            ndev, packet->q_idx));
+                                            ndev, q_idx));
 
                         if (atomic_read(&net_device->
-                                queue_sends[packet->q_idx]) < 1)
+                                queue_sends[q_idx]) < 1)
                                 netif_tx_wake_queue(netdev_get_tx_queue(
-                                                    ndev, packet->q_idx));
+                                                    ndev, q_idx));
                 }
         } else if (ret == -EAGAIN) {
                 netif_tx_stop_queue(netdev_get_tx_queue(
-                                    ndev, packet->q_idx));
-                if (atomic_read(&net_device->queue_sends[packet->q_idx]) < 1) {
+                                    ndev, q_idx));
+                if (atomic_read(&net_device->queue_sends[q_idx]) < 1) {
                         netif_tx_wake_queue(netdev_get_tx_queue(
-                                            ndev, packet->q_idx));
+                                            ndev, q_idx));
                         ret = -ENOSPC;
                 }
         } else {