hv_netvsc: Fix validation in netvsc_linkstatus_callback()

Contrary to the RNDIS protocol specification, certain (pre-Fe)
implementations of Hyper-V's vSwitch did not account for the status
buffer field in the length of an RNDIS packet; the bug was fixed in
newer implementations.  Validate the status buffer fields using the
length of the 'vmtransfer_page' packet (all implementations), that
is known/validated to be less than or equal to the receive section
size and not smaller than the length of the RNDIS message.

Reported-by: Dexuan Cui <decui@microsoft.com>
Suggested-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Fixes: 505e3f00c3f36 ("hv_netvsc: Add (more) validation for untrusted Hyper-V values")
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index e1a497d..59ac04a 100644 (file)
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -229,7 +229,7 @@ int netvsc_send(struct net_device *net,
                bool xdp_tx);
 void netvsc_linkstatus_callback(struct net_device *net,
                                struct rndis_message *resp,
-                               void *data);
+                               void *data, u32 data_buflen);
 int netvsc_recv_callback(struct net_device *net,
                         struct netvsc_device *nvdev,
                         struct netvsc_channel *nvchan);

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 8176fa0..15f262b 100644 (file)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -744,7 +744,7 @@ static netdev_tx_t netvsc_start_xmit(struct sk_buff *skb,
  */
 void netvsc_linkstatus_callback(struct net_device *net,
                                struct rndis_message *resp,
-                               void *data)
+                               void *data, u32 data_buflen)
 {
        struct rndis_indicate_status *indicate = &resp->msg.indicate_status;
        struct net_device_context *ndev_ctx = netdev_priv(net);
@@ -765,11 +765,16 @@ void netvsc_linkstatus_callback(struct net_device *net,
        if (indicate->status == RNDIS_STATUS_LINK_SPEED_CHANGE) {
                u32 speed;
 
-               /* Validate status_buf_offset */
+               /* Validate status_buf_offset and status_buflen.
+                *
+                * Certain (pre-Fe) implementations of Hyper-V's vSwitch didn't account
+                * for the status buffer field in resp->msg_len; perform the validation
+                * using data_buflen (>= resp->msg_len).
+                */
                if (indicate->status_buflen < sizeof(speed) ||
                    indicate->status_buf_offset < sizeof(*indicate) ||
-                   resp->msg_len - RNDIS_HEADER_SIZE < indicate->status_buf_offset ||
-                   resp->msg_len - RNDIS_HEADER_SIZE - indicate->status_buf_offset
+                   data_buflen - RNDIS_HEADER_SIZE < indicate->status_buf_offset ||
+                   data_buflen - RNDIS_HEADER_SIZE - indicate->status_buf_offset
                                < indicate->status_buflen) {
                        netdev_err(net, "invalid rndis_indicate_status packet\n");
                        return;

diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 123cc9d..c0e89e1 100644 (file)
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -620,7 +620,7 @@ int rndis_filter_receive(struct net_device *ndev,
 
        case RNDIS_MSG_INDICATE:
                /* notification msgs */
-               netvsc_linkstatus_callback(ndev, rndis_msg, data);
+               netvsc_linkstatus_callback(ndev, rndis_msg, data, buflen);
                break;
        default:
                netdev_err(ndev,