[PATCH net v2 1/4] net: netlink: fix sending unassigned nsid after assigned one

[Ilya Maximets]

If the current skb is not shared, it is re-used directly for all the
sockets subscribed to the notification.  If we have remote all-nsid
socket receiving a message first, then the 'nsid_is_set' will be
set to 'true'.  If the nsid is NOT_ASSIGNED for the next socket in
the list, the 'nsid_is_set' will remain 'true' and the negative value
is be delivered to the user space.  All subsequent nsid values will be
delivered as well, since there is no code path that sets the flag
back to 'false'.

Fix that by always dropping the flag to 'false' first.

Fixes: 7212462fa6fd ("netlink: don't send unknown nsid")
Signed-off-by: Ilya Maximets <i.maxim...@ovn.org>
---
 net/netlink/af_netlink.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 2aeb0680807d6..0742e97f256e4 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1482,6 +1482,7 @@ static void do_one_broadcast(struct sock *sk,
                p->skb2 = NULL;
                goto out;
        }
+       NETLINK_CB(p->skb2).nsid_is_set = false;
        NETLINK_CB(p->skb2).nsid = peernet2id(sock_net(sk), p->net);
        if (NETLINK_CB(p->skb2).nsid != NETNSA_NSID_NOT_ASSIGNED)
                NETLINK_CB(p->skb2).nsid_is_set = true;
-- 
2.53.0