Subject: Re: [PATCH] vhost_net: initialize rx_ring in vhost_net_open()

From: Eric Dumazet <[email-masked]>
Date: Thu, 8 Mar 2018 07:45:17 -0800

On 03/08/2018 07:20 AM, Alexander Potapenko wrote:
> On Thu, Mar 8, 2018 at 4:15 PM, Eric Dumazet <[email-masked]> 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 <[email-masked]>
>>
>>
>> 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.

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);
>>>
>>
> 
> 
>