On Tue, Jul 22, 2025 at 07:32:30PM -0500, Chenyuan Yang wrote:
> The xdp_convert_buff_to_frame() function can return NULL when there is
> insufficient headroom in the buffer to store the xdp_frame structure
> or when the driver didn't reserve enough tailroom for skb_shared_info.
>
> Currently, the sfc siena driver does not check for this NULL return value
> in the XDP_TX case within efx_do_xdp().
>
> Fix by adding a proper NULL check in the XDP_TX case. If conversion
> fails, free the RX buffer and increment the bad drops counter, following
> the same pattern used for other XDP error conditions in this driver.
>
> Signed-off-by: Chenyuan Yang <chenyuan0y@xxxxxxxxx>
> Fixes: d48523cb88e0 ("sfc: Copy shared files needed for Siena (part 2)")
> ---
> drivers/net/ethernet/sfc/siena/rx.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/ethernet/sfc/siena/rx.c b/drivers/net/ethernet/sfc/siena/rx.c
> index 98d3c0743c0f..65f6daad3168 100644
> --- a/drivers/net/ethernet/sfc/siena/rx.c
> +++ b/drivers/net/ethernet/sfc/siena/rx.c
> @@ -310,6 +310,12 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
> case XDP_TX:
> /* Buffer ownership passes to tx on success. */
> xdpf = xdp_convert_buff_to_frame(&xdp);
> + if (unlikely(!xdpf)) {
> + efx_siena_free_rx_buffers(rx_queue, rx_buf, 1);
> + channel->n_rx_xdp_bad_drops++;
> + break;
> + }
I see the incidence of this cleanup code multiplying in this function.
I would be nice to follow-up by consolidating that - I'd suggest
in the form of a goto label at the end of the function.
But as a fix for net this minimal patch seems appropriate to me.
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
> +
> err = efx_siena_xdp_tx_buffers(efx, 1, &xdpf, true);
> if (unlikely(err != 1)) {
> efx_siena_free_rx_buffers(rx_queue, rx_buf, 1);
> --
> 2.34.1
>
>
