Subject: Re: [RFC] net: usbnet: prevent buggy devices from killing us

From: Sergei Shtylyov <[email-masked]>
Date: Thu, 24 Jan 2013 16:39:18 +0400

Hello.

On 24-01-2013 14:25, 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. We handle the done queue as fast as we can, so
> if this queue is filling up then that is an indication that we
> are under too heavy pressure.  Refusing further allocations
> until the done queue is handled prevents the buggy device
> from taking the system down.
>
> Signed-off-by: Bjørn Mork <[email-masked]>
[...]

>   drivers/net/usb/usbnet.c |    8 ++++++++
>   1 files changed, 8 insertions(+), 0 deletions(-)

> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
> index f34b2eb..85c7ffd 100644
> --- a/drivers/net/usb/usbnet.c
> +++ b/drivers/net/usb/usbnet.c
> @@ -380,6 +380,14 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
>   	unsigned long		lockflags;
>   	size_t			size = dev->rx_urb_size;
>
> +	/* Do not let a device flood us to death! */
> +	if (dev->done.qlen > 1024) {
> +		netif_dbg(dev, rx_err, dev->net, "done queue filling up (%u) - throttling\n", dev->done.qlen);
> +		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
> +		usb_free_urb (urb);

    Run your patch thru scripts/checkpatch.pl please -- spaces before parens 
are not allowed.

WBR, Sergei