[net-2.6] bonding: correctly process LACPDUs in non-linear skbs

It was recently brought to my attention that 802.3ad mode bonds would no
longer form when using some network hardware after a driver update.
After snooping around I realized that the particular hardware was using
page-based skbs and found that skb->data did not contain a valid LACPDU
as it wasn't stored there.  That explained the inability to form an
802.3ad-based bond.

This patch fixes the issue in my tests and should be applied to 2.6.36
and as far back as anyone cares to add it to stable.

Thanks to Alexander Duyck <alexander.h.duyck@intel.com> and Jesse
Brandeburg <jesse.brandeburg@intel.com> for the suggestions on this one.

Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Jesse Brandeburg <jesse.brandeburg@intel.com>
CC: stable@kernel.org

---
 drivers/net/bonding/bond_3ad.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

Andy Gospodarek <andy@greyhouse.net> wrote:

>
>It was recently brought to my attention that 802.3ad mode bonds would no
>longer form when using some network hardware after a driver update.
>After snooping around I realized that the particular hardware was using
>page-based skbs and found that skb->data did not contain a valid LACPDU
>as it wasn't stored there.  That explained the inability to form an
>802.3ad-based bond.
>
>This patch fixes the issue in my tests and should be applied to 2.6.36
>and as far back as anyone cares to add it to stable.
>
>Thanks to Alexander Duyck <alexander.h.duyck@intel.com> and Jesse
>Brandeburg <jesse.brandeburg@intel.com> for the suggestions on this one.
>
>Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
>CC: Alexander Duyck <alexander.h.duyck@intel.com>
>CC: Jesse Brandeburg <jesse.brandeburg@intel.com>
>CC: stable@kernel.org

	Did you by any chance also test balance-alb mode?  Inspection
suggests that rlb_arp_recv may suffer from the same problem.

	If you agree, could you add that to the patch and resubmit it?

	Either way, the patch looks good.

	-J

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>


>---
> drivers/net/bonding/bond_3ad.c |    3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>index 822f586..0ddf4c6 100644
>--- a/drivers/net/bonding/bond_3ad.c
>+++ b/drivers/net/bonding/bond_3ad.c
>@@ -2466,6 +2466,9 @@ int bond_3ad_lacpdu_recv(struct sk_buff *skb, struct net_device *dev, struct pac
> 	if (!(dev->flags & IFF_MASTER))
> 		goto out;
>
>+	if (!pskb_may_pull(skb, sizeof(struct lacpdu)))
>+		goto out;
>+
> 	read_lock(&bond->lock);
> 	slave = bond_get_slave_by_dev((struct bonding *)netdev_priv(dev),
> 					orig_dev);
>-- 
>1.7.0.1
>
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