On 06.03.2023 15:07, Stefano Garzarella wrote:
> On Sun, Mar 05, 2023 at 11:08:38PM +0300, Arseniy Krasnov wrote:
>> This fixes two things in case when 'memcpy_to_msg()' fails:
>> 1) Update credit parameters of the socket, like this skbuff was
>> copied to user successfully. This is needed because when skbuff was
>> received it's length was used to update 'rx_bytes', thus when we drop
>> skbuff here, we must account rest of it's data in 'rx_bytes'.
>> 2) Free skbuff which was removed from socket's queue.
>>
>> Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
>> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
>> ---
>> net/vmw_vsock/virtio_transport_common.c | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>> index 30b0539990ba..ffb1af4f2b52 100644
>> --- a/net/vmw_vsock/virtio_transport_common.c
>> +++ b/net/vmw_vsock/virtio_transport_common.c
>> @@ -379,8 +379,12 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
>> spin_unlock_bh(&vvs->rx_lock);
>>
>> err = memcpy_to_msg(msg, skb->data, bytes);
>> - if (err)
>> + if (err) {
>> + skb_pull(skb, skb->len);
>> + virtio_transport_dec_rx_pkt(vvs, skb);
>> + consume_skb(skb);
>
> I'm not sure it's the right thing to do, if we fail to copy the content
> into the user's buffer, I think we should queue it again.
>
> In fact, before commit 71dc9ec9ac7d ("virtio/vsock: replace
> virtio_vsock_pkt with sk_buff"), we used to remove the packet from the
> rx_queue, only if memcpy_to_msg() was successful.
>
> Maybe it is better to do as we did before and use skb_peek() at the
> beginning of the loop and __skb_unlink() when skb->len == 0.
Yes, i see. I'll also add test to cover this case.
>
> Thanks,
> Stefano
>
>> goto out;
>> + }
>>
>> spin_lock_bh(&vvs->rx_lock);
>>
>> --
>> 2.25.1
>>
>
