[PATCH 2/4] ethtool: ensure channel counts are within bounds during SCHANNELS

[Jacob Keller]

Add a sanity check to ensure that all requested channel sizes are within
bounds, which should reduce errors in driver implementation.

Signed-off-by: Jacob Keller <jacob.e.kel...@intel.com>
---
 net/core/ethtool.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 8a40948c1fc6..71aff99157c3 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1276,16 +1276,27 @@ static noinline_for_stack int 
ethtool_get_channels(struct net_device *dev,
 static noinline_for_stack int ethtool_set_channels(struct net_device *dev,
                                                   void __user *useraddr)
 {
-       struct ethtool_channels channels;
+       struct ethtool_channels channels, max;
        u32 max_rx = 0;
        int ret;
 
-       if (!dev->ethtool_ops->set_channels)
+       if (!dev->ethtool_ops->set_channels || !dev->ethtool_ops->get_channels)
                return -EOPNOTSUPP;
 
        if (copy_from_user(&channels, useraddr, sizeof(channels)))
                return -EFAULT;
 
+       ret = dev->ethtool_ops->get_channels(dev, &max);
+       if (ret)
+               return ret;
+
+       /* ensure new counts are within the maximums */
+       if ((channels.rx_count > max.max_rx) ||
+           (channels.tx_count > max.max_tx) ||
+           (channels.combined_count > max.max_combined) ||
+           (channels.other_count > max.max_other))
+               return -EINVAL;
+
        /* ensure the new Rx count fits within the configured Rx flow
         * indirection table settings */
        if (netif_is_rxfh_configured(dev) &&
-- 
2.7.0.236.gda096a0.dirty