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SubjectRe: [PATCH net] ip6tnl: fix use after free of fb_tnl_dev
On Thu, Nov 14, 2013 at 9:47 AM, Nicolas Dichtel
<nicolas.dichtel@6wind.com> wrote:
> Bug has been introduced by commit bb8140947a24 ("ip6tnl: allow to use rtnl ops
> on fb tunnel").
>
> When ip6_tunnel.ko is unloaded, FB device is delete by rtnl_link_unregister()
> and then we try to use the pointer in ip6_tnl_destroy_tunnels().
>
> Let's add an handler for dellink, which will never remove the FB tunnel. With
> this patch it will no more be possible to remove it via 'ip link del ip6tnl0',
> but it's safer.
>
> The same fix was already proposed by Willem de Bruijn <willemb@google.com> for
> sit interfaces.
>
> CC: Willem de Bruijn <willemb@google.com>
> Reported-by: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>

Acked-by: Willem de Bruijn <willemb@google.com>

Also ran a test similar to the one for sit: `modprobe ip6_tunnel;
rmmod ip6_tunnel` with CONFIG_DEBUG_SLAB=y. This exposed the bug at
HEAD, completes successfully with the patch applied.


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