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OVS: Ignore negative headroom value

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net_device->ndo_set_rx_headroom (introduced in
871b642ade) says

  "Setting a negtaive value reset the rx headroom
   to the default value".

It seems that the OVS implementation in
3a927bc7cf overlooked this and sets
dev->needed_headroom unconditionally.

This doesn't have an immediate effect, but can mess up later
LL_RESERVED_SPACE calculations, such as done in
net/ipv6/mcast.c:mld_newpack.  For reference, this issue was found
from a skb_panic raised there after the length calculations had given
the wrong result.

Note the other current users of this interface
(drivers/net/tun.c:tun_set_headroom and
drivers/net/veth.c:veth_set_rx_headroom) are both checking this
correctly thus need no modification.

Thanks to Ben for some pointers from the crash dumps!

Cc: Benjamin Poirier <bpoirier@suse.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1361414
Signed-off-by: Ian Wienand <iwienand@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ian Wienand 2016-08-03 15:44:57 +10:00 committed by David S. Miller
parent 7cf210dc26
commit 5ef9f289c4
1 changed files with 1 additions and 1 deletions
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2
net/openvswitch/vport-internal_dev.c
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@ -140,7 +140,7 @@ internal_get_stats(struct net_device *dev, struct rtnl_link_stats64 *stats)
static void internal_set_rx_headroom(struct net_device *dev, int new_hr)
{
dev->needed_headroom = new_hr;
dev->needed_headroom = new_hr < 0 ? 0 : new_hr;
}
static const struct net_device_ops internal_dev_netdev_ops = {