net/mlx5e: Fix operation precedence bug in port timestamping napi_poll context

Indirection (*) is of lower precedence than postfix increment (++). Logic
in napi_poll context would cause an out-of-bound read by first increment
the pointer address by byte address space and then dereference the value.
Rather, the intended logic was to dereference first and then increment the
underlying value.

Fixes: 92214be5979c ("net/mlx5e: Update doorbell for port timestamping CQ before the software counter")
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
index c206cc0a84832e6ebf104cc92990c43a81e94d60..078f56a3cbb2b389499c0b609908972af691a41c 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
@@ -213,7 +213,7 @@ static void mlx5e_ptp_handle_ts_cqe(struct mlx5e_ptpsq *ptpsq,
        mlx5e_ptpsq_mark_ts_cqes_undelivered(ptpsq, hwtstamp);
 out:
        napi_consume_skb(skb, budget);
-       md_buff[*md_buff_sz++] = metadata_id;
+       md_buff[(*md_buff_sz)++] = metadata_id;
        if (unlikely(mlx5e_ptp_metadata_map_unhealthy(&ptpsq->metadata_map)) &&
            !test_and_set_bit(MLX5E_SQ_STATE_RECOVERING, &sq->state))
                queue_work(ptpsq->txqsq.priv->wq, &ptpsq->report_unhealthy_work);