Re: [PATCH] net: thunderx: prevent concurrent data re-writing by nicvf_set_rx_mode

[David Miller]

From: Vadim Lomovtsev <Vadim.Lomovtsev@xxxxxxxxxxxxxxxxxx>
Date: Fri,  8 Jun 2018 02:27:59 -0700

> +	/* Save message data locally to prevent them from
> +	 * being overwritten by next ndo_set_rx_mode call().
> +	 */
> +	spin_lock(&nic->rx_mode_wq_lock);
> +	mode = vf_work->mode;
> +	mc = vf_work->mc;
> +	vf_work->mc = NULL;
> +	spin_unlock(&nic->rx_mode_wq_lock);

At the moment you drop this lock, the memory behind 'mc' can be
freed up by:

> +	spin_lock(&nic->rx_mode_wq_lock);
> +	kfree(nic->rx_mode_work.mc);

And you'll crash when you dereference it above via
__nicvf_set_rx_mode_task().