[1/2] e1000e: Don't return uninitialized stats

Some statistics passed to ethtool are garbage because e1000e_get_stats64()
doesn't write them, for example: tx_heartbeat_errors. This leaks kernel
memory to userspace and confuses users.

Do like ixgbe and use dev_get_stats() which first zeroes out
rtnl_link_stats64.

Reported-by: Stefan Priebe <s.priebe@profihost.ag>
Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
---
 drivers/net/ethernet/intel/e1000e/ethtool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On 4/23/2017 15:53, Neftin, Sasha wrote:
> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@lists.osuosl.org] On Behalf Of Benjamin Poirier
> Sent: Saturday, April 22, 2017 00:20
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com>
> Cc: netdev@vger.kernel.org; intel-wired-lan@lists.osuosl.org; Stefan Priebe <s.priebe@profihost.ag>
> Subject: [Intel-wired-lan] [PATCH 1/2] e1000e: Don't return uninitialized stats
>
> Some statistics passed to ethtool are garbage because e1000e_get_stats64() doesn't write them, for example: tx_heartbeat_errors. This leaks kernel memory to userspace and confuses users.
>
> Do like ixgbe and use dev_get_stats() which first zeroes out rtnl_link_stats64.
>
> Reported-by: Stefan Priebe <s.priebe@profihost.ag>
> Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
> ---
>   drivers/net/ethernet/intel/e1000e/ethtool.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/e1000e/ethtool.c b/drivers/net/ethernet/intel/e1000e/ethtool.c
> index 7aff68a4a4df..f117b90cdc2f 100644
> --- a/drivers/net/ethernet/intel/e1000e/ethtool.c
> +++ b/drivers/net/ethernet/intel/e1000e/ethtool.c
> @@ -2063,7 +2063,7 @@ static void e1000_get_ethtool_stats(struct net_device *netdev,
>   
>   	pm_runtime_get_sync(netdev->dev.parent);
>   
> -	e1000e_get_stats64(netdev, &net_stats);
> +	dev_get_stats(netdev, &net_stats);
>   
>   	pm_runtime_put_sync(netdev->dev.parent);
>   
> --
> 2.12.2
>
> _______________________________________________
> Intel-wired-lan mailing list
> Intel-wired-lan@lists.osuosl.org
> http://lists.osuosl.org/mailman/listinfo/intel-wired-lan

Hello,

We would like to not accept this patch. Suggested generic method 
'*dev_get_stats' (net/core/dev.c) calls 'ops->ndo_get_stats64' method 
which eventually calls e1000e_get_stats64 (netdev.c) - so there is same 
functionality. Also, see that 'e1000e_get_stats64' method in netdev.c 
(line 5928) calls 'memset' with 0's before update statistics.  Local 
sanity check in our lab shows 'tx_heartbeat_errors' counter reported as 0.

Thanks,

Sasha

Dear Benjamin,


Thank you for your fix.

On 04/21/17 23:20, Benjamin Poirier wrote:
> Some statistics passed to ethtool are garbage because e1000e_get_stats64()
> doesn't write them, for example: tx_heartbeat_errors. This leaks kernel
> memory to userspace and confuses users.

Could you please give specific examples to reproduce the issue? That way 
your fix can also be tested.

[…]


Kind regards,

Paul

Sasha, please use reply-all to keep everyone in cc (including me...).

On 2017/04/24 11:17, Neftin, Sasha wrote:
> On 4/23/2017 15:53, Neftin, Sasha wrote:
> > -----Original Message-----
> > From: Intel-wired-lan [mailto:intel-wired-lan-bounces@lists.osuosl.org] On Behalf Of Benjamin Poirier
> > Sent: Saturday, April 22, 2017 00:20
> > To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com>
> > Cc: netdev@vger.kernel.org; intel-wired-lan@lists.osuosl.org; Stefan Priebe <s.priebe@profihost.ag>
> > Subject: [Intel-wired-lan] [PATCH 1/2] e1000e: Don't return uninitialized stats
> > 
> > Some statistics passed to ethtool are garbage because e1000e_get_stats64() doesn't write them, for example: tx_heartbeat_errors. This leaks kernel memory to userspace and confuses users.
> > 
> > Do like ixgbe and use dev_get_stats() which first zeroes out rtnl_link_stats64.
> > 
> > Reported-by: Stefan Priebe <s.priebe@profihost.ag>
> > Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
> > ---
> >   drivers/net/ethernet/intel/e1000e/ethtool.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/intel/e1000e/ethtool.c b/drivers/net/ethernet/intel/e1000e/ethtool.c
> > index 7aff68a4a4df..f117b90cdc2f 100644
> > --- a/drivers/net/ethernet/intel/e1000e/ethtool.c
> > +++ b/drivers/net/ethernet/intel/e1000e/ethtool.c
> > @@ -2063,7 +2063,7 @@ static void e1000_get_ethtool_stats(struct net_device *netdev,
> >   	pm_runtime_get_sync(netdev->dev.parent);
> > -	e1000e_get_stats64(netdev, &net_stats);
> > +	dev_get_stats(netdev, &net_stats);
> >   	pm_runtime_put_sync(netdev->dev.parent);
> > --
> > 2.12.2
> > 
> > _______________________________________________
> > Intel-wired-lan mailing list
> > Intel-wired-lan@lists.osuosl.org
> > http://lists.osuosl.org/mailman/listinfo/intel-wired-lan
> 
> Hello,
> 
> We would like to not accept this patch. Suggested generic method
> '*dev_get_stats' (net/core/dev.c) calls 'ops->ndo_get_stats64' method which
> eventually calls e1000e_get_stats64 (netdev.c) - so there is same
> functionality. Also, see that 'e1000e_get_stats64' method in netdev.c (line

No, it's not the same functionality because dev_get_stats() does a
memset on the rtnl_link_stats64 struct.

> 5928) calls 'memset' with 0's before update statistics.  Local sanity check

I don't see any memset in e1000e_get_stats64(). What kernel version are
you looking at?

> in our lab shows 'tx_heartbeat_errors' counter reported as 0.
> 

Please see the mail I just sent to Paul Menzel <pmenzel@molgen.mpg.de>
for more information about the issue and how to reproduce it.