netdev - Re: [PATCH] ipv6: fix race between ipv6_del

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Message-Id: <20080708.151404.177911457.davem@davemloft.net>
Date:	Tue, 08 Jul 2008 15:14:04 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	xemul@...nvz.org
Cc:	yoshfuji@...ux-ipv6.org, netdev@...r.kernel.org,
	avagin@...allels.com
Subject: Re: [PATCH] ipv6: fix race between ipv6_del_addr and DAD timer

From: Pavel Emelyanov <xemul@...nvz.org>
Date: Tue, 08 Jul 2008 12:55:24 +0400

> Consider the following scenario:
> 
> ipv6_del_addr(ifp)
>   ipv6_ifa_notify(RTM_DELADDR, ifp)
>     ip6_del_rt(ifp->rt)
> 
> after returning from the ipv6_ifa_notify and enabling BH-s
> back, but *before* calling the addrconf_del_timer the 
> ifp->timer fires and:
> 
> addrconf_dad_timer(ifp)
>   addrconf_dad_completed(ifp)
>     ipv6_ifa_notify(RTM_NEWADDR, ifp)
>       ip6_ins_rt(ifp->rt)
> 
> then return back to the ipv6_del_addr and:
> 
> in6_ifa_put(ifp)
>   inet6_ifa_finish_destroy(ifp)
>     dst_release(&ifp->rt->u.dst)
> 
> After this we have an ifp->rt inserted into fib6 lists, but 
> queued for gc, which in turn can result in oopses in the
> fib6_run_gc. Maybe some other nasty things, but we caught 
> only the oops in gc so far.
> 
> The solution is to disarm the ifp->timer before flushing the
> rt from it.
> 
> Signed-off-by: Andrey Vagin <avagin@...allels.com>
> Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>

Applied to net-2.6, thanks a lot for this bug fix!
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