Re: [PATCH net 2/2] octeon_ep_vf: fix skb frags overflow in the RX path

[Maciej Fijalkowski]

On Wed, Jul 01, 2026 at 07:28:25PM +0800, Maoyi Xie wrote:
> __octep_vf_oq_process_rx() has the same unbounded fragment loop as the PF
> driver. buff_info->len comes from the device response header, and one
> fragment is added per buffer_size chunk with no check against
> MAX_SKB_FRAGS. A long packet yields about 18 fragments, one past the
> default MAX_SKB_FRAGS of 17, so skb_add_rx_frag() writes past
> shinfo->frags[].
> 
> The driver now drops a packet that would need more fragments than the skb
> can hold. It drains the descriptors the same way the build_skb failure
> path does.
> 
> Fixes: 1cd3b407977c ("octeon_ep_vf: add Tx/Rx processing and interrupt support")
> Co-developed-by: Kaixuan Li <kaixuan.li@xxxxxxxxxx>
> Signed-off-by: Kaixuan Li <kaixuan.li@xxxxxxxxxx>
> Signed-off-by: Maoyi Xie <maoyixie.tju@xxxxxxxxx>
> ---
>  .../ethernet/marvell/octeon_ep_vf/octep_vf_rx.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c
> index d982474082423..2e666df26b4c3 100644
> --- a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c
> +++ b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c
> @@ -463,6 +463,23 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct,
>  
>  			shinfo = skb_shinfo(skb);
>  			data_len = buff_info->len - oq->max_single_buffer_size;
> +			if (DIV_ROUND_UP(data_len, oq->buffer_size) > MAX_SKB_FRAGS) {
> +				dev_kfree_skb_any(skb);
> +				while (data_len) {
> +					dma_unmap_page(oq->dev, oq->desc_ring[read_idx].buffer_ptr,
> +						       PAGE_SIZE, DMA_FROM_DEVICE);
> +					buff_info = (struct octep_vf_rx_buffer *)
> +						    &oq->buff_info[read_idx];
> +					buff_info->page = NULL;
> +					if (data_len < oq->buffer_size)
> +						data_len = 0;
> +					else
> +						data_len -= oq->buffer_size;
> +					desc_used++;
> +					read_idx = octep_vf_oq_next_idx(oq, read_idx);
> +				}
> +				continue;
> +			}

same suggestion/question here pluse there seems to be a bunch of repeated
code between linear and non-linear skb processing paths...

>  			while (data_len) {
>  				dma_unmap_page(oq->dev, oq->desc_ring[read_idx].buffer_ptr,
>  					       PAGE_SIZE, DMA_FROM_DEVICE);
> -- 
> 2.34.1
> 
>