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

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Message-Id: <20140401.162717.1962834632849633175.davem@davemloft.net>
Date:	Tue, 01 Apr 2014 16:27:17 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	wei.liu2@...rix.com
Cc:	netdev@...r.kernel.org, xen-devel@...ts.xen.org,
	david.vrabel@...rix.com, zoltan.kiss@...rix.com, edwin@...rok.net,
	ian.campbell@...rix.com
Subject: Re: [PATCH v4 net] xen-netback: disable rogue vif in kthread
 context

From: Wei Liu <wei.liu2@...rix.com>
Date: Tue, 1 Apr 2014 12:46:12 +0100

> 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.
> 
> Reported-by: Török Edwin <edwin@...rok.net>
> Signed-off-by: Wei Liu <wei.liu2@...rix.com>

Applied.
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