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>
5ef9f289c4