[ovs-dev] [PATCH] pkt reassemble: fix kernel panic for ovs reassemble

Joe Stringer joe at ovn.org
Fri Jul 21 18:28:55 UTC 2017


On 6 July 2017 at 13:57, Ben Pfaff <blp at ovn.org> wrote:
> From: wangzhike <wangzhike at jd.com>
>
> Ovs and kernel stack would add frag_queue to same netns_frags list.
> As result, ovs and kernel may access the fraq_queue without correct
> lock. Also the struct ipq may be different on kernel(older than 4.3),
> which leads to invalid pointer access.
>
> The fix creates specific netns_frags for ovs.
>
> Signed-off-by: wangzhike <wangzhike at jd.com>
> ---

Hi,

Thanks a lot for your hard work on this. I know through the several
revisions of private review we did, you considered several options for
how to better structure this, and I don't see a straightforward way to
improve it any further.

I've run this patch dozens of times on a variety of kernel versions,
and at this point I am at this point reasonably confident that it
doesn't make the current fragmentation situation worse. Given that it
fixes a problem that you have been hitting, I think that the best way
for this to get more testing is for us to apply it. If there are
subsequent future issues with this code, then we can always deal with
that at a later time. Given the nature of bugs that affect this area
of the code--that is to say, racy---I am not currently intending to
backport this patch to earlier branches. It will however become part
of the upcoming OVS 2.8 release.

I applied this patch to master.

Thanks,
Joe


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