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Date: Fri, 31 Jul 2020 11:27:03 -0600 From: David Ahern <dsahern@...il.com> To: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>, netdev@...r.kernel.org Cc: bridge@...ts.linux-foundation.org, roopa@...ulusnetworks.com, davem@...emloft.net Subject: Re: [PATCH net] net: bridge: clear bridge's private skb space on xmit On 7/31/20 10:26 AM, Nikolay Aleksandrov wrote: > We need to clear all of the bridge private skb variables as they can be > stale due to the packet being recirculated through the stack and then > transmitted through the bridge device. Similar memset is already done on > bridge's input. We've seen cases where proxyarp_replied was 1 on routed > multicast packets transmitted through the bridge to ports with neigh > suppress which were getting dropped. Same thing can in theory happen with > the port isolation bit as well. > > Fixes: 821f1b21cabb ("bridge: add new BR_NEIGH_SUPPRESS port flag to suppress arp and nd flood") > Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com> > --- > net/bridge/br_device.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c > index 8c7b78f8bc23..9a2fb4aa1a10 100644 > --- a/net/bridge/br_device.c > +++ b/net/bridge/br_device.c > @@ -36,6 +36,8 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev) > const unsigned char *dest; > u16 vid = 0; > > + memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); > + > rcu_read_lock(); > nf_ops = rcu_dereference(nf_br_ops); > if (nf_ops && nf_ops->br_dev_xmit_hook(skb)) { > What's the performance hit of doing this on every packet? Can you just set a flag that tells the code to reset on recirculation? Seems like br_input_skb_cb has space for that.
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