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

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Message-ID: <533AACC6.3050200@citrix.com>
Date:	Tue, 1 Apr 2014 13:10:46 +0100
From:	David Vrabel <david.vrabel@...rix.com>
To:	Wei Liu <wei.liu2@...rix.com>
CC:	<netdev@...r.kernel.org>, <xen-devel@...ts.xen.org>,
	<zoltan.kiss@...rix.com>, <edwin@...rok.net>,
	Ian Campbell <ian.campbell@...rix.com>
Subject: Re: [PATCH v4 net] xen-netback: disable rogue vif in kthread context

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>

David
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