Re: [PATCH net 4/4] virito-net: fix leaking page for gso packet during mergeable XDP

Jason Wang
2018-05-22T03:37:47Z

On 2018年05月21日 23:01, Michael S. Tsirkin wrote:
> On Mon, May 21, 2018 at 04:35:06PM +0800, Jason Wang wrote:
>> We need to drop refcnt to xdp_page if we see a gso packet. Otherwise
>> it will be leaked. Fixing this by moving the check of gso packet above
>> the linearizing logic.
>>
>> Cc: John Fastabend <john.fastabend@gmail.com>
>> Fixes: 72979a6c3590 ("virtio_net: xdp, add slowpath case for non contiguous buffers")
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
> typo in subject

Let me fix it in V2.

>> ---
>> drivers/net/virtio_net.c | 16 ++++++++--------
>> 1 file changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 165a922..f8db809 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -707,6 +707,14 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>> void *data;
>> u32 act;
>>
>> + /* Transient failure which in theory could occur if
>> + * in-flight packets from before XDP was enabled reach
>> + * the receive path after XDP is loaded. In practice I
>> + * was not able to create this condition.
> BTW we should probably drop the last sentence. It says in theory, should be enough.

Ok.

Thanks

>> + */
>> + if (unlikely(hdr->hdr.gso_type))
>> + goto err_xdp;
>> +
>> /* This happens when rx buffer size is underestimated
>> * or headroom is not enough because of the buffer
>> * was refilled before XDP is set. This should only
>> @@ -728,14 +736,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>> xdp_page = page;
>> }
>>
>> - /* Transient failure which in theory could occur if
>> - * in-flight packets from before XDP was enabled reach
>> - * the receive path after XDP is loaded. In practice I
>> - * was not able to create this condition.
>> - */
>> - if (unlikely(hdr->hdr.gso_type))
>> - goto err_xdp;
>> -
>> /* Allow consuming headroom but reserve enough space to push
>> * the descriptor on if we get an XDP_TX return code.
>> */
>> --
>> 2.7.4