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

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Date:	Fri, 25 Jan 2013 13:02:38 +0100
From:	Oliver Neukum <oliver@...kum.org>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	linux-usb@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net] net: usbnet: prevent buggy devices from killing us

On Friday 25 January 2013 08:13:15 Bjørn Mork wrote:
> Oliver Neukum <oliver@...kum.org> writes:
> > On Thursday 24 January 2013 20:16:56 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.
> >> 
> >> Temporarily disable RX skb allocation and URB submission when
> >> the current error ratio is high, preventing us from trying to
> >> allocate an infinite number of skbs.  Reenable as soon as we
> >> are finished processing the done queue, allowing the device
> >> to continue working after short error bursts.
> >> 
> >> Signed-off-by: Bjørn Mork <bjorn@...k.no>
> >> ---
> >> So is this starting to look OK?
> >
> > It seems to me that we at least need to try some error recovery.
> 
> Won't the disabling code in usbnet_bh do? RX will only stay disabled
> until the done queue is handled.

So will the burst of bogus packets stop by itself?

> 
> > How about resetting the device when it is no longer used?
> 
> Yes, that we should do. I guess usbnet_open is the place to reset the
> flag and counters? I'll send another version taking care of this and
> Joes comment.

I was thinking about resetting the device, not just counters.
But yes, open() needs to reset the counters, too.

	Regards
		Oliver

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