Re: [PATCH 1/2] neigh: fix possible DoS due to net iface start/stop loop

David Ahern
2022-08-01T15:08:47Z

On 7/29/22 4:35 AM, Alexander Mikhalitsyn wrote:
> The patch proposed doing very simple thing. It drops only packets from

it does 2 things - adds a namespace check and a performance based change
with the way the list is walked.

> the same namespace in the pneigh_queue_purge() where network interface
> state change is detected. This is enough to prevent the problem for the
> whole node preserving original semantics of the code.
>

> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 54625287ee5b..213ec0be800b 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c

> @@ -386,8 +396,7 @@ static int __neigh_ifdown(struct neigh_table *tbl, struct net_device *dev,
> neigh_flush_dev(tbl, dev, skip_perm);
> pneigh_ifdown_and_unlock(tbl, dev);
>
> - del_timer_sync(&tbl->proxy_timer);

why are you removing this line too?

> - pneigh_queue_purge(&tbl->proxy_queue);
> + pneigh_queue_purge(&tbl->proxy_queue, dev_net(dev));
> return 0;
> }
>