netdev - Re: [PATCH 4.19 1/1] net: bridge: clear bridge's private skb space on xmit

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Date:   Thu, 27 Jan 2022 16:39:41 +0100
From:   Greg KH <greg@...ah.com>
To:     Huang Guobin <huangguobin4@...wei.com>
Cc:     nikolay@...ulusnetworks.com, roopa@...ulusnetworks.com,
        davem@...emloft.net, bridge@...ts.linux-foundation.org,
        netdev@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 4.19 1/1] net: bridge: clear bridge's private skb space
 on xmit

On Wed, Jan 26, 2022 at 11:36:39AM +0800, Huang Guobin wrote:
> From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
> 
> [ Upstream commit fd65e5a95d08389444e8591a20538b3edece0e15 ]
> 
> 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>
> Signed-off-by: David S. Miller <davem@...emloft.net>
> Signed-off-by: Huang Guobin <huangguobin4@...wei.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 a350c05b7ff5..7c6b1024dd4b 100644
> --- a/net/bridge/br_device.c
> +++ b/net/bridge/br_device.c
> @@ -42,6 +42,8 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
>  	struct ethhdr *eth;
>  	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)) {
> -- 
> 2.25.1
> 

Now queued up, thanks.

greg k-h