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

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Apr 02, 2014 at 10:05:40AM +0100, Ian Campbell wrote:
> On Tue, 2014-04-01 at 16:27 -0400, David Miller wrote:
> > From: Wei Liu <wei.liu2@xxxxxxxxxx>
> > 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@xxxxxxxxxx>
> > > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> > 
> > Applied.
> 
> Thanks.
> 
> Wei -- can you advise as to which stable trees this should be queued
> for? Looks like 3.12 onwards according to
> http://xenbits.xen.org/xsa/advisory-90.html which says the issue arose
> between 3.11 and 3.12-rc1?
> 

Correct.

Wei.

> Cheers,
> Ian.
> 

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