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@xxxxxxxxxxxxx>
Suggested-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
Fixes: 505e3f00c3f36 ("hv_netvsc: Add (more) validation for untrusted Hyper-V values")
---
drivers/net/hyperv/hyperv_net.h | 2 +-
drivers/net/hyperv/netvsc_drv.c | 13 +++++++++----
drivers/net/hyperv/rndis_filter.c | 2 +-
3 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index e1a497d3c9ba4..59ac04a610adb 100644
--- 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 8176fa0c8b168..15f262b70489e 100644
--- 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 123cc9d25f5ed..c0e89e107d575 100644
--- 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,
--
2.25.1
