Re: [PATCH] xen-netfront: handle NULL returned by xdp_convert_buff_to_frame()

Jürgen Groß
2025-04-17T07:12:05Z

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On 17.04.25 09:00, Alexey wrote:
>
> On 17.04.2025 03:58, Jakub Kicinski wrote:
>> On Mon, 14 Apr 2025 18:34:01 +0000 Alexey Nepomnyashih wrote:
>>>           get_page(pdata);
>> Please notice this get_page() here.
>>
>>>           xdpf = xdp_convert_buff_to_frame(xdp);
>>> +        if (unlikely(!xdpf)) {
>>> +            trace_xdp_exception(queue->info->netdev, prog, act);
>>> +            break;
>>> +        }
> Do you mean that it would be better to move the get_page(pdata) call lower,
> after checking for NULL in xdpf, so that the reference count is only increased
> after a successful conversion?

I think the error handling here is generally broken (or at least very
questionable).

I suspect that in case of at least some errors the get_page() is leaking
even without this new patch.

In case I'm wrong a comment reasoning why there is no leak should be
added.

Juergen

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