[PATCH 3.16.y-ckt 009/126] sit: fix sit0 percpu double allocations

[Ben Hutchings]

On Wed, 2015-12-09 at 09:36 +0000, Luis Henriques wrote:
> 3.16.7-ckt21 -stable review patch.  If anyone has any objections,
> please let me know.
> 
> ------------------
> 
> From: Eric Dumazet <edumazet at google.com>
> 
> commit 4ece9009774596ee3df0acba65a324b7ea79387c upstream.
> 
> sit0 device allocates its percpu storage twice :
> - One time in ipip6_tunnel_init()
> - One time in ipip6_fb_tunnel_init()
> 
> Thus we leak 48 bytes per possible cpu per network namespace
> dismantle.
> 
> ipip6_fb_tunnel_init() can be much simpler and does not
> return an error, and should be called after register_netdev()
[...]

Doesn't this introduce a race condition when sit is a module?  There
seems to be nothing to prevent access to the partially initialised
device after calling register_netdev(), if sit_init_net() is called
during module loading rather than during namespace creation.

Ben.

-- 
Ben Hutchings
Knowledge is power.  France is bacon.
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