On 2/25/2011 4:21 PM, Ben Hutchings wrote:

On Fri, 2011-02-25 at 15:32 -0800, Alexander Duyck wrote:

quoted

This change is meant to prevent a possible null pointer dereference if
NETIF_F_NTUPLE is defined but the set_rx_ntuple function pointer is not.

I think it would be a bug for NETIF_F_NTUPLE to be enabled on a device
that doesn't have this operation.  Are there any drivers for which this
is possible?

Currently there are no drivers where this is possible.  However I 
encountered it as a result of testing the patches further on in this set.

quoted

This issue appears to affect all kernels since 2.6.34.

If this can actually happen, the fix should go to net-2.6 and
stable@kernel.org.  However, I think that the null deference is
impossible and this really just fixes the error code.

Ben.

It cannot occur with any of the in-kernel drivers since they all set the 
NETIF_F_NTUPLE flag and have the function defined.  However going 
forward I would like to have the option of using the network flow 
classifier interface instead of the set_rx_ntuple interface due to the 
fact that it supports many of the features I needed.

I believe this patch should apply to net-2.6 without any changes so if 
it is better placed there I will resubmit it specifically for net-2.6 
and stable.

Thanks,

Alex

quoted

Signed-off-by: Alexander Duyck<redacted>
---

  net/core/ethtool.c |    3 +++
  1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index c1a71bb..4843674 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c

@@ -893,6 +893,9 @@ static noinline_for_stack int ethtool_set_rx_ntuple(struct net_device *dev,
  	struct ethtool_rx_ntuple_flow_spec_container *fsc = NULL;
  	int ret;

+	if (!ops->set_rx_ntuple)
+		return -EOPNOTSUPP;
+
  	if (!(dev->features&  NETIF_F_NTUPLE))
  		return -EINVAL;