netdev - Re: [PATCH v4 net] xen-netback: disable rogue vif in kthread context

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Date:	Tue, 1 Apr 2014 13:19:18 +0100
From:	Ian Campbell <Ian.Campbell@...rix.com>
To:	David Vrabel <david.vrabel@...rix.com>
CC:	Wei Liu <wei.liu2@...rix.com>, <netdev@...r.kernel.org>,
	<xen-devel@...ts.xen.org>, <zoltan.kiss@...rix.com>,
	<edwin@...rok.net>
Subject: Re: [PATCH v4 net] xen-netback: disable rogue vif in kthread context

On Tue, 2014-04-01 at 13:10 +0100, David Vrabel wrote:
> On 01/04/14 12:46, Wei Liu wrote:
> > When netback discovers frontend is sending malformed packet it will
> > disables the interface which serves that frontend.
> > 
> > However disabling a network interface involving taking a mutex which
> > cannot be done in softirq context, so we need to defer this process to
> > kthread context.
> > 
> > This patch does the following:
> > 1. introduce a flag to indicate the interface is disabled.
> > 2. check that flag in TX path, don't do any work if it's true.
> > 3. check that flag in RX path, turn off that interface if it's true.
> > 
> > The reason to disable it in RX path is because RX uses kthread. After
> > this change the behavior of netback is still consistent -- it won't do
> > any TX work for a rogue frontend, and the interface will be eventually
> > turned off.
> > 
> > Also change a "continue" to "break" after xenvif_fatal_tx_err, as it
> > doesn't make sense to continue processing packets if frontend is rogue.
> > 
> > This is a fix for XSA-90.
> 
> Reviewed-by: David Vrabel <david.vrabel@...rix.com>

Acked-by: Ian Campbell <ian.campbell@...rix.com>

Ian.


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