Re: [PATCH net] openvswitch: Fix skb leak in IPv6 reassembly.

On Tue, Nov 29, 2016 at 12:54 AM, Daniele Di Proietto
[off-list ref] wrote:

2016-11-28 23:39 GMT-08:00 Pravin Shelar [off-list ref]:

quoted

On Mon, Nov 28, 2016 at 3:43 PM, Daniele Di Proietto
[off-list ref] wrote:

quoted

If nf_ct_frag6_gather() returns an error other than -EINPROGRESS, it
means that we still have a reference to the skb.  We should free it
before returning from handle_fragments, as stated in the comment above.

Fixes: daaa7d647f81 ("netfilter: ipv6: avoid nf_iterate recursion")
CC: Florian Westphal <fw@strlen.de>
CC: Pravin B Shelar <redacted>
CC: Joe Stringer <redacted>
Signed-off-by: Daniele Di Proietto <redacted>
---
 net/openvswitch/conntrack.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 31045ef..fecefa2 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c

@@ -370,8 +370,11 @@ static int handle_fragments(struct net *net, struct

sw_flow_key *key,
                skb_orphan(skb);
                memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
                err = nf_ct_frag6_gather(net, skb, user);
-               if (err)
+               if (err) {
+                       if (err != -EINPROGRESS)
+                               kfree_skb(skb);
                        return err;
+               }

This fixes the code. But the patch is adding yet another skb-kfree in
conntrack code. we could simplify it by reusing error handling in
do_execute_actions().
If you think that is too complicated for stable branch, I am fine with
this patch going in as it is.

I thought it was simpler to handle this here rather than changing the
interface of
handle_fragments() and ovs_ct_execute(). Also this is more similar to the v4
case,
where ip_defrag() frees the skb in case of error.

What do you think?

I agree this is simple enough for stable branch. I will check if ct
action error handling could be simplified bit.

Acked-by: Pravin B Shelar <redacted>