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

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Date:   Thu, 8 Mar 2018 16:20:49 +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 4:15 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")

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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