net/mlx5e: kTLS, Fix napi sync and possible use-after-free

Using synchronize_rcu() is sufficient to wait until running NAPI quits.

See similar upstream fix with detailed explanation:
("net/mlx5e: Use synchronize_rcu to sync with NAPI")

This change also fixes a possible use-after-free as the NAPI
might be already released at this stage.

Fixes: 0419d8c9d8f8 ("net/mlx5e: kTLS, Add kTLS RX resync support")
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
index acf6d80..f95aa50 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
@@ -659,7 +659,7 @@ void mlx5e_ktls_del_rx(struct net_device *netdev, struct tls_context *tls_ctx)
        priv_rx = mlx5e_get_ktls_rx_priv_ctx(tls_ctx);
        set_bit(MLX5E_PRIV_RX_FLAG_DELETING, priv_rx->flags);
        mlx5e_set_ktls_rx_priv_ctx(tls_ctx, NULL);
-       napi_synchronize(&priv->channels.c[priv_rx->rxq]->napi);
+       synchronize_rcu(); /* Sync with NAPI */
        if (!cancel_work_sync(&priv_rx->rule.work))
                /* completion is needed, as the priv_rx in the add flow
                 * is maintained on the wqe info (wi), not on the socket.