netdev - Re: [PATCH net] ipv4: igmp: fix refcnt uaf issue when receiving igmp query packet

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Message-ID: <9a221a65-71ae-2bca-e33c-f62c6b625461@huawei.com>
Date: Tue, 21 Nov 2023 20:38:34 +0800
From: shaozhengchao <shaozhengchao@...wei.com>
To: Hangbin Liu <liuhangbin@...il.com>
CC: <netdev@...r.kernel.org>, <davem@...emloft.net>, <dsahern@...nel.org>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<weiyongjun1@...wei.com>, <yuehaibing@...wei.com>
Subject: Re: [PATCH net] ipv4: igmp: fix refcnt uaf issue when receiving igmp
 query packet



On 2023/11/21 10:56, Hangbin Liu wrote:
> Hi Zhengchao,
> On Tue, Nov 21, 2023 at 10:05:58AM +0800, Zhengchao Shao wrote:
>> ---
>>   net/ipv4/igmp.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
>> index 76c3ea75b8dd..f217581904d6 100644
>> --- a/net/ipv4/igmp.c
>> +++ b/net/ipv4/igmp.c
>> @@ -1044,6 +1044,8 @@ static bool igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb,
>>   	for_each_pmc_rcu(in_dev, im) {
>>   		int changed;
>>   
>> +		if (!netif_running(im->interface->dev))
>> +			continue;
> 
> I haven't checked this part for a long time. What's the difference of in_dev->dev
> and im->interface->dev? I though they are the same, no?
> 
> If they are the same, should we stop processing the query earlier? e.g.
> 

Hi Hangbin:
	Yes, they are the same.

> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index 76c3ea75b8dd..f4e1d229c9aa 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -1082,6 +1082,9 @@ int igmp_rcv(struct sk_buff *skb)
>                          goto drop;
>          }
> 
> +       if (!netif_running(dev))
> +               goto drop;
> +
>          in_dev = __in_dev_get_rcu(dev);
>          if (!in_dev)
>                  goto drop;
> 
> 
> BTW, does IPv6 MLD has this issue?

I will take a look at IPv6 MLD later. maybe tonight.
Thank you.

Zhengchao Shao
> 
> Thanks
> Hangbin
>