netdev - Re: Possible refcount bug in ip6_expire_frag

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Message-ID: <052c350a-5076-283b-9679-eec21a827b54@canonical.com>
Date:   Fri, 3 May 2019 14:07:00 +0200
From:   Stefan Bader <stefan.bader@...onical.com>
To:     Eric Dumazet <edumazet@...gle.com>,
        Peter Oskolkov <posk@...gle.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>
Subject: Re: Possible refcount bug in ip6_expire_frag_queue()?

On 03.05.19 13:49, Eric Dumazet wrote:
> On Fri, May 3, 2019 at 7:17 AM Eric Dumazet <edumazet@...gle.com> wrote:
>>
>> On Fri, May 3, 2019 at 7:12 AM Eric Dumazet <edumazet@...gle.com> wrote:
>>>
> 
>>> I will send the following fix
>>>
>>> diff --git a/include/net/ipv6_frag.h b/include/net/ipv6_frag.h
>>> index 28aa9b30aeceac9a86ee6754e4b5809be115e947..d3152811b8962705a508b3fd31d2157dd19ae8e5
>>> 100644
>>> --- a/include/net/ipv6_frag.h
>>> +++ b/include/net/ipv6_frag.h
>>> @@ -94,11 +94,9 @@ ip6frag_expire_frag_queue(struct net *net, struct
>>> frag_queue *fq)
>>>                 goto out;
>>>
>>>         head->dev = dev;
>>> -       skb_get(head);
>>>         spin_unlock(&fq->q.lock);
>>>
>>>         icmpv6_send(head, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0);
>>> -       kfree_skb(head);
>>
>> Oh well, we want to keep the kfree_skb() of course.
>>
>> Only the skb_get(head) needs to be removed (this would fix memory leak
>> I presume...  :/ )
> 
> Official submission :
> 
> https://patchwork.ozlabs.org/patch/1094854/ ip6: fix skb leak in
> ip6frag_expire_frag_queue()
> 
> Thanks a lot Stefan for bringing up this issue to our attention !
> 
Thank you Eric for the quick response.

-Stefan



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