netdev - Re: [PATCH net] net: usbnet: prevent buggy devices from killing us

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Date:	Thu, 24 Jan 2013 15:57:09 -0800
From:	Joe Perches <joe@...ches.com>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	Oliver Neukum <oneukum@...e.de>, linux-usb@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH net] net: usbnet: prevent buggy devices from killing us

On Thu, 2013-01-24 at 20:16 +0100, Bjørn Mork wrote:
> A device sending 0 length frames as fast as it can has been
> observed killing the host system due to the resulting memory
> pressure.
[]
> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
[]
> @@ -539,6 +545,22 @@ block:
>  		break;
>  	}
>  
> +	/* stop rx if packet error rate is high */
> +	if (++dev->pkt_cnt > 30) {
> +		dev->pkt_cnt = 0;
> +		dev->pkt_err = 0;
> +	} else {
> +		if (state == rx_cleanup)
> +			dev->pkt_err++;
> +		if (dev->pkt_err > 20) {
> +			set_bit(EVENT_RX_KILL, &dev->flags);
> +			if (net_ratelimit())
> +				netif_dbg(dev, rx_err, dev->net,
> +					  "rx kill: high error rate\n");
> +			dev->pkt_err = 0;
> +		}
> +	}

Maybe use ratelimit() here?

> diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
[]
> @@ -33,6 +33,7 @@ struct usbnet {
>  	wait_queue_head_t	*wait;
>  	struct mutex		phy_mutex;
>  	unsigned char		suspend_count;
> +	unsigned char		pkt_cnt, pkt_err;

and instead:

	struct ratelimit_state errors;



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