ethtool: do not set some flags, if others failed

NETIF_F_NTUPLE flag setting introduced a bug:  non-ntuple flags
like LRO may be successfully set, before ioctl(2) returns failure
to userspace.

The set-flags operation should be all-or-none, rather than leaving
things in an inconsistent state prior to reporting failure to
userspace.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 4 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 31b1eddc1b84..0f2f82185ec4 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -135,21 +135,23 @@ u32 ethtool_op_get_flags(struct net_device *dev)
 int ethtool_op_set_flags(struct net_device *dev, u32 data)
 {
         const struct ethtool_ops *ops = dev->ethtool_ops;
+        unsigned long features = dev->features;
 
         if (data & ETH_FLAG_LRO)
-                dev->features |= NETIF_F_LRO;
+                features |= NETIF_F_LRO;
         else
-                dev->features &= ~NETIF_F_LRO;
+                features &= ~NETIF_F_LRO;
 
         if (data & ETH_FLAG_NTUPLE) {
                 if (!ops->set_rx_ntuple)
                         return -EOPNOTSUPP;
-                dev->features |= NETIF_F_NTUPLE;
+                features |= NETIF_F_NTUPLE;
         } else {
                 /* safe to clear regardless */
-                dev->features &= ~NETIF_F_NTUPLE;
+                features &= ~NETIF_F_NTUPLE;
         }
 
+        dev->features = features;
         return 0;
 }