Re: [PATCH net] ipvs: fix crash if scheduler is changed

To: Simon Horman <horms@xxxxxxxxxxxx>
Subject: Re: [PATCH net] ipvs: fix crash if scheduler is changed
Cc: lvs-devel@xxxxxxxxxxxxxxx, Alexander Vasiliev <a.vasylev@xxxxxxxxxxxxx>
From: Julian Anastasov <ja@xxxxxx>
Date: Mon, 29 Jun 2015 21:50:25 +0300 (EEST)

On Mon, 29 Jun 2015, Simon Horman wrote:

> On Sat, Jun 27, 2015 at 02:37:42PM +0300, Julian Anastasov wrote:
> > I overlooked the svc->sched_data usage from schedulers
> > when the services were converted to RCU in 3.10. Now
> > the rare ipvsadm -E command can change the scheduler
> > but due to the reverse order of ip_vs_bind_scheduler
> > and ip_vs_unbind_scheduler we provide new sched_data
> > to the old scheduler resulting in a crash.
> > 
> > To fix it without changing the scheduler methods we
> > have to use synchronize_rcu() only for the editing case.
> > It means all svc->scheduler readers should expect a
> > NULL value. To avoid breakage for the service listing
> > and ipvsadm -R we can use the "none" name to indicate
> > that scheduler is not assigned, a state when we drop
> > new connections.
> > 
> > Reported-by: Alexander Vasiliev <a.vasylev@xxxxxxxxxxxxx>
> > Fixes: ceec4c381681 ("ipvs: convert services to rcu")
> > Signed-off-by: Julian Anastasov <ja@xxxxxx>
> Thanks, I have applied this to the ipvs tree.

        Simon, I'm sending v2 due to the build error...
which was somehow missed by my compiler...


Julian Anastasov <ja@xxxxxx>
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