ip: ip_ra_control() rcu fix

commit 66018506e15b (ip: Router Alert RCU conversion) introduced RCU
lookups to ip_call_ra_chain(). It missed proper deinit phase :
When ip_ra_control() deletes an ip_ra_chain, it should make sure
ip_call_ra_chain() users can not start to use socket during the rcu
grace period. It should also delay the sock_put() after the grace
period, or we risk a premature socket freeing and corruptions, as
raw sockets are not rcu protected yet.

This delay avoids using expensive atomic_inc_not_zero() in
ip_call_ra_chain().

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 9982c97f0bdc..d52f01180361 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -61,7 +61,10 @@ struct ipcm_cookie {
 struct ip_ra_chain {
         struct ip_ra_chain      *next;
         struct sock             *sk;
-        void                    (*destructor)(struct sock *);
+        union {
+                void                    (*destructor)(struct sock *);
+                struct sock             *saved_sk;
+        };
         struct rcu_head         rcu;
 };