From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <erdnetdev@gmail.com>
Subject: Re: NULL pointer dereference in veth_stats_one
Date: Fri, 04 Jan 2013 11:23:26 -0800
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Cc: Tom Parkin <tparkin@katalix.com>,
	David Miller <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>
To: Ben Hutchings <bhutchings@solarflare.com>
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On Fri, 2013-01-04 at 18:17 +0000, Ben Hutchings wrote:

> This possibly needs some memory barriers to properly synchronise with
> veth_newlink().  But can you not move initialisation of the peer
> pointers before registration of the devices in veth_newlink(), so that
> veth_get_stats64() cannot be called before they are initialised?

The ->peer pointer cannot change once set. ( its never cleared )

So the problem would not be in veth_newlink(), but might be in
veth_dellink()

It seems we would have a problem in veth_get_ethtool_stats() already...

More generally, what prevents a get_stats() being called while a
dellink() (-> veth_dev_free() -> free_percpu()) is done ?

(Same thing is done for tunnel/dummy stats percpu data)