hyperv: Fix RNDIS send_completion code path

In some cases, the VM_PKT_COMP message can arrive later than RNDIS completion
message, which will free the packet memory. This may cause panic due to access
to freed memory in netvsc_send_completion().

This patch fixes this problem by removing rndis_filter_send_request_completion()
from the code path. The function was a no-op.

Reported-by: Long Li <longli@microsoft.com>
Tested-by: Long Li <longli@microsoft.com>
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>

2 files changed, 13 insertions, 18 deletions

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 1cd77483da50..f5f0f09e4cc5 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -470,8 +470,10 @@ static void netvsc_send_completion(struct hv_device *device,
                         packet->trans_id;
 
                 /* Notify the layer above us */
-                nvsc_packet->completion.send.send_completion(
-                        nvsc_packet->completion.send.send_completion_ctx);
+                if (nvsc_packet)
+                        nvsc_packet->completion.send.send_completion(
+                                nvsc_packet->completion.send.
+                                send_completion_ctx);
 
                 num_outstanding_sends =
                         atomic_dec_return(&net_device->num_outstanding_sends);
@@ -498,6 +500,7 @@ int netvsc_send(struct hv_device *device,
         int ret = 0;
         struct nvsp_message sendMessage;
         struct net_device *ndev;
+        u64 req_id;
 
         net_device = get_outbound_net_device(device);
         if (!net_device)
@@ -518,20 +521,24 @@ int netvsc_send(struct hv_device *device,
                 0xFFFFFFFF;
         sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_size = 0;
 
+        if (packet->completion.send.send_completion)
+                req_id = (u64)packet;
+        else
+                req_id = 0;
+
         if (packet->page_buf_cnt) {
                 ret = vmbus_sendpacket_pagebuffer(device->channel,
                                                   packet->page_buf,
                                                   packet->page_buf_cnt,
                                                   &sendMessage,
                                                   sizeof(struct nvsp_message),
-                                                  (unsigned long)packet);
+                                                  req_id);
         } else {
                 ret = vmbus_sendpacket(device->channel, &sendMessage,
                                 sizeof(struct nvsp_message),
-                                (unsigned long)packet,
+                                req_id,
                                 VM_PKT_DATA_INBAND,
                                 VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-
         }
 
         if (ret == 0) {
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 2b657d4d63a8..0775f0aefd1e 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -61,9 +61,6 @@ struct rndis_request {
 
 static void rndis_filter_send_completion(void *ctx);
 
-static void rndis_filter_send_request_completion(void *ctx);
-
-
 
 static struct rndis_device *get_rndis_device(void)
 {
@@ -241,10 +238,7 @@ static int rndis_filter_send_request(struct rndis_device *dev,
                         packet->page_buf[0].len;
         }
 
-        packet->completion.send.send_completion_ctx = req;/* packet; */
-        packet->completion.send.send_completion =
-                rndis_filter_send_request_completion;
-        packet->completion.send.send_completion_tid = (unsigned long)dev;
+        packet->completion.send.send_completion = NULL;
 
         ret = netvsc_send(dev->net_dev->dev, packet);
         return ret;
@@ -999,9 +993,3 @@ static void rndis_filter_send_completion(void *ctx)
         /* Pass it back to the original handler */
         filter_pkt->completion(filter_pkt->completion_ctx);
 }
-
-
-static void rndis_filter_send_request_completion(void *ctx)
-{
-        /* Noop */
-}