hv_netvsc: Add validation for untrusted Hyper-V values

For additional robustness in the face of Hyper-V errors or malicious
behavior, validate all values that originate from packets that Hyper-V
has sent to the guest in the host-to-guest ring buffer. Ensure that
invalid values cannot cause indexing off the end of an array, or
subvert an existing validation via integer overflow. Ensure that
outgoing packets do not have any leftover guest memory that has not
been zeroed out.

Signed-off-by: Andres Beltran <[email protected]>
Co-developed-by: Andrea Parri (Microsoft) <[email protected]>
Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: [email protected]
Reviewed-by: Haiyang Zhang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index b7db3766f5b9..9869e390875e 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -748,6 +748,13 @@ void netvsc_linkstatus_callback(struct net_device *net,
 	struct netvsc_reconfig *event;
 	unsigned long flags;
 
+	/* Ensure the packet is big enough to access its fields */
+	if (resp->msg_len - RNDIS_HEADER_SIZE < sizeof(struct rndis_indicate_status)) {
+		netdev_err(net, "invalid rndis_indicate_status packet, len: %u\n",
+			   resp->msg_len);
+		return;
+	}
+
 	/* Update the physical link speed when changing to another vSwitch */
 	if (indicate->status == RNDIS_STATUS_LINK_SPEED_CHANGE) {
 		u32 speed;