netdev - Re: [PATCH] vhost_net: initialize rx_ring in vhost_net

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Date:   Thu, 8 Mar 2018 16:50:29 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Dmitriy Vyukov <dvyukov@...gle.com>, jasowang@...hat.com,
        mst@...hat.com, kvm@...r.kernel.org,
        Networking <netdev@...r.kernel.org>
Subject: Re: [PATCH] vhost_net: initialize rx_ring in vhost_net_open()

On Thu, Mar 8, 2018 at 4:45 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
> On 03/08/2018 07:20 AM, Alexander Potapenko wrote:
>>
>> On Thu, Mar 8, 2018 at 4:15 PM, Eric Dumazet <eric.dumazet@...il.com>
>> wrote:
>>>
>>>
>>>
>>> On 03/08/2018 05:37 AM, Alexander Potapenko wrote:
>>>>
>>>>
>>>> KMSAN reported a use of uninit memory in vhost_net_buf_unproduce()
>>>> while trying to access n->vqs[VHOST_NET_VQ_TX].rx_ring:
>>>>
>>>>
>>>> ==================================================================
>>>>
>>>> Signed-off-by: Alexander Potapenko <glider@...gle.com>
>>>
>>>
>>>
>>> Please identify bug origin with a Fixes: tag
>>
>> Fixes: 5990a30510ed1 ("tun/tap: use ptr_ring instead of skb_array")
>
>
> Please send a V2 with this added tag. patchwork does not recognize it yet.
Ok, will do. Thanks for reminding about the tag!
> David Miller has also a lot on his plate, please everybody be gentle with
> both stable teams and maintainers.
>
> Thanks.
>
>
>
>>
>> The above patch introduced rx_ring, but the problem existed before.
>>
>>> This will tremendously help stable teams that are struggling with many
>>> backports these days.
>>>
>>> Thanks.
>>>
>>>
>>>> ---
>>>>    drivers/vhost/net.c | 1 +
>>>>    1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
>>>> index 610cba276d47..60f1080bffc7 100644
>>>> --- a/drivers/vhost/net.c
>>>> +++ b/drivers/vhost/net.c
>>>> @@ -948,6 +948,7 @@ static int vhost_net_open(struct inode *inode,
>>>> struct
>>>> file *f)
>>>>                  n->vqs[i].done_idx = 0;
>>>>                  n->vqs[i].vhost_hlen = 0;
>>>>                  n->vqs[i].sock_hlen = 0;
>>>> +               n->vqs[i].rx_ring = NULL;
>>>>                  vhost_net_buf_init(&n->vqs[i].rxq);
>>>>          }
>>>>          vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
>>>>
>>>
>>
>>
>>
>



-- 
Alexander Potapenko
Software Engineer

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