Re: [PATCH RESEND] netfilter: bridge: unshare bridge info before change it

[Gao feng <gaofeng@cn.fujitsu.com>]

On 11/19/2014 02:34 AM, Pablo Neira Ayuso wrote:
> On Mon, Nov 17, 2014 at 01:48:43PM +0800, Gao feng wrote:
>> diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
>> index 1a4f32c..b4612b9 100644
>> --- a/net/bridge/br_netfilter.c
>> +++ b/net/bridge/br_netfilter.c
>> @@ -653,7 +643,11 @@ static int br_nf_forward_finish(struct sk_buff *skb)
>>  		in = nf_bridge->physindev;
>>  		if (nf_bridge->mask & BRNF_PKT_TYPE) {
>>  			skb->pkt_type = PACKET_OTHERHOST;
>> -			nf_bridge->mask ^= BRNF_PKT_TYPE;
>> +
>> +			if (!nf_bridge_unset_mask(skb, BRNF_PKT_TYPE)) {
>> +				kfree_skb(skb);
>> +				return 0;
>> +			}
> 
> This can now release the packet and, thus, drop it.
> 
> However, br_nf_forward_ip() always returns NF_STOLEN.
> 
> Could you revisit the error paths and confirm they are correct?

Since br_nf_forward_ip() returns NF_STOLEN, br_nf_forward_finish should make
sure this skb will be released. if unser_mask for this skb is failed, we free
it. if unset successed, the hooks on NF_BR_FORWARD or br_forward_finish will
free this skb.

I check the error paths again, find a missing null check of nf_bridge. I will
post v2 patch.