Hi!
> commit 3116f59c12bd24c513194cd3acb3ec1f7d468954 upstream.
>
> Using ifconfig command to delete the ipv6 address will cause
> the i40e network card driver to delete its internal mac_filter and
> i40e_service_task kernel thread will concurrently access the mac_filter.
> These two processes are not protected by lock
> so causing the following use-after-free problems.
Ok, but...
> +static void netdev_hw_addr_refcnt(struct i40e_mac_filter *f,
> + struct net_device *netdev, int delta)
> +{
> + struct netdev_hw_addr *ha;
> +
> + if (!f || !netdev)
> + return;
> +
> + netdev_for_each_mc_addr(ha, netdev) {
> + if (ether_addr_equal(ha->addr, f->macaddr)) {
> + ha->refcount += delta;
> + if (ha->refcount <= 0)
> + ha->refcount = 1;
> + break;
> + }
> + }
> +}
What is going on here? Is refcount expected to underflow under normal
operation? Should we at least have WARN_ON there?
Best regards,
Pavel
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