Messages in this thread | | | Subject | Re: [PATCH 3.16.y-ckt 009/126] sit: fix sit0 percpu double allocations | From | Ben Hutchings <> | Date | Sun, 13 Dec 2015 20:20:35 +0000 |
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On Sun, 2015-12-13 at 18:54 +0000, Luis Henriques wrote: > On Sat, Dec 12, 2015 at 04:18:26AM +0000, Ben Hutchings wrote: > > 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@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. > > > > This seems to be an upstream issue, not specific to the 3.16.y-ckt > stable kernel. If that is the case, I guess I'll just keep this patch > and later apply the fix. Or do you think this race is really likely > to be a worst problem than then issue the patch is trying to fix?
It seems worse than the problem being fixed.
Ben.
-- Ben Hutchings Life would be so much easier if we could look at the source code.[unhandled content-type:application/pgp-signature] | |