Re: [PATCH 0/2] [BUG FIXES - 3.10.27] sit: More backports

[Nicolas Dichtel]

Le 28/01/2014 21:57, Steven Rostedt a Ãcrit :
> At Red Hat we base our real-time kernel off of 3.10.27 and do lots of
> stress testing on that kernel. This has discovered some bugs that we
> can hit with the vanilla 3.10.27 kernel (no -rt patches applied).
>
> I sent out a bug fix that can cause a crash with the current 3.10.27
> when you add and then remove the sit module. That patch is obsoleted by
> these patches, as that patch was not enough.
Can you explain a bit more which problem remains after that patch?
I wonder if a problem remains also with ip6_tunnel.ko (net/ipv6/ip6_tunnel.c),
the same problem was spotted into this module.

> A previous patch that was backported:
>
>    Upstream commit 205983c43700ac3a81e7625273a3fa83cd2759b5
>    sit: allow to use rtnl ops on fb tunnel
>
> Had a depenency on commit 5e6700b3bf98 ("sit: add support of x-netns")
> which was not backported. The dependency was only on part of that
> commit which is what I backported.
I cannot comment directly the patch, it was an attachement, hence I put my
comments here.
In patch 0001-sit-Unregister-sit-devices-with-rtnl_link_ops.patch, I wonder how
'if (dev_net(t->dev) != net)' can be wrong. If commit 5e6700b3bf98 ("sit: add
support of x-netns") has not been backported, this test is always true.

> The other upstream commit 9434266f2c645d4fcf62a03a8e36ad8075e37943
> sit: fix use after free of fb_tunnel_dev
>
> fixes another bug we encountered, it also fixes the 3.10.27 bug
> where removing the sit module cause the crash. This is the patch
> that obsoletes my previous patch.
>
> -- Steve
>
>
> Steven Rostedt (Red Hat) (1):
>        sit: Unregister sit devices with rtnl_link_ops
>
> Willem de Bruijn (1):
>        sit: fix use after free of fb_tunnel_dev
>
> ----
>   net/ipv6/sit.c | 30 +++++++++++++++++++++++++-----
>   1 file changed, 25 insertions(+), 5 deletions(-)
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