linux-kernel - Re: [PATCH linux-2.6 v2] IPv6: Temp addresses are immediately deleted.

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Message-Id: <20100928.233028.112599117.davem@davemloft.net>
Date:	Tue, 28 Sep 2010 23:30:28 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	gwurster@....carleton.ca
Cc:	kuznet@....inr.ac.ru, pekkas@...core.fi, jmorris@...ei.org,
	yoshfuji@...ux-ipv6.org, kaber@...sh.net, shemminger@...tta.com,
	eric.dumazet@...il.com, herbert@...dor.apana.org.au,
	ebiederm@...ssion.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH linux-2.6 v2] IPv6: Temp addresses are immediately
 deleted.

From: Glenn Wurster <gwurster@....carleton.ca>
Date: Mon, 27 Sep 2010 13:10:10 -0400

> There is a bug in the interaction between ipv6_create_tempaddr and 
> addrconf_verify.  Because ipv6_create_tempaddr uses the cstamp and tstamp 
> from the public address in creating a private address, if we have not 
> received a router advertisement in a while, tstamp + temp_valid_lft might be 
> < now.  If this happens, the new address is created inside 
> ipv6_create_tempaddr, then the loop within addrconf_verify starts again and 
> the address is immediately deleted.  We are left with no temporary addresses 
> on the interface, and no more will be created until the public IP address is 
> updated.  To avoid this, set the expiry time to be the minimum of the time 
> left on the public address or the config option PLUS the current age of the 
> public interface.
> 
> Version 2, now with 100% fewer line wraps.  Thanks to David Miller for
> pointing out the line wrapping issue.
> 
> Signed-off-by: Glenn Wurster <gwurster@....carleton.ca>

This can only happen if we apply your other patch, which I showed
was incorrect as per RFCs.

We only create temporary address when public addresses are created,
and this is the point where we are handling a router advertisement
with non-zero Valid Lifetime.

Therefore I'm not applying this patch either.

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