igbvf: integer wrapping bug setting the mtu

If new_mtu is very large then "new_mtu + ETH_HLEN + ETH_FCS_LEN" can
wrap and the check on the next line can underflow. This is one of those
bugs which can be triggered by the user if you have namespaces
configured.

Also since this is something the user can trigger then we don't want to
have dev_err() message.

This is a static checker fix and I'm not sure what the impact is.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Tested-by: Sibai Li Sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c
index 93eb7ee06d3e0aa2159fcccc61e797eb44fd79bd..f48ae71f0d47167233b1a599eb1c9ff617bef53d 100644 (file)
--- a/drivers/net/ethernet/intel/igbvf/netdev.c
+++ b/drivers/net/ethernet/intel/igbvf/netdev.c
@@ -2343,10 +2343,9 @@ static int igbvf_change_mtu(struct net_device *netdev, int new_mtu)
        struct igbvf_adapter *adapter = netdev_priv(netdev);
        int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN;
 
-       if ((new_mtu < 68) || (max_frame > MAX_JUMBO_FRAME_SIZE)) {
-               dev_err(&adapter->pdev->dev, "Invalid MTU setting\n");
+       if (new_mtu < 68 || new_mtu > INT_MAX - ETH_HLEN - ETH_FCS_LEN ||
+           max_frame > MAX_JUMBO_FRAME_SIZE)
                return -EINVAL;
-       }
 
 #define MAX_STD_JUMBO_FRAME_SIZE 9234
        if (max_frame > MAX_STD_JUMBO_FRAME_SIZE) {