Re: [PATCH net v3 2/2] mlx5: fix possible ptp queue fifo use-after-free

[Rahul Rameshbabu <rrameshbabu@nvidia.com>]

On Thu, 26 Jan, 2023 04:02:06 +0300 Vadim Fedorenko <vfedorenko@novek.ru> wrote:
> From: Vadim Fedorenko <vadfed@meta.com>
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
> index b72de2b520ec..4ac7483dcbcc 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
> @@ -94,14 +94,23 @@ static void mlx5e_ptp_skb_fifo_ts_cqe_resync(struct mlx5e_ptpsq *ptpsq, u16 skb_
>  
>  	ptpsq->cq_stats->resync_event++;
>  
> -	while (skb_cc != skb_id) {
> -		skb = mlx5e_skb_fifo_pop(&ptpsq->skb_fifo);
> +	if (skb_cc > skb_id || PTP_WQE_CTR2IDX(ptpsq->skb_fifo_pc) < skb_id)
> +		pr_err_ratelimited("mlx5e: out-of-order ptp cqe\n");

Lets use mlx5_core_err_rl(ptpsq->txqsq.mdev, "out-of-order ptp cqe\n") instead?

> +		return false;
> +	}
> +
> +	while (skb_cc != skb_id && (skb = mlx5e_skb_fifo_pop(&ptpsq->skb_fifo))) {
>  		hwts.hwtstamp = mlx5e_skb_cb_get_hwts(skb)->cqe_hwtstamp;
>  		skb_tstamp_tx(skb, &hwts);
>  		ptpsq->cq_stats->resync_cqe++;
>  		napi_consume_skb(skb, budget);
>  		skb_cc = PTP_WQE_CTR2IDX(ptpsq->skb_fifo_cc);
>  	}