IB/core: Unregister notifier before freeing MAD security

If the notifier runs after the security context is freed an access of
freed memory can occur.

Fixes: 47a2b338fe ("IB/core: Enforce security on management datagrams")
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/security.c

@@ -727,9 +727,10 @@ void ib_mad_agent_security_cleanup(struct ib_mad_agent *agent)
 	if (!rdma_protocol_ib(agent->device, agent->port_num))
 		return;
 
-	security_ib_free_security(agent->security);
 	if (agent->lsm_nb_reg)
 		unregister_lsm_notifier(&agent->lsm_nb);
+
+	security_ib_free_security(agent->security);
 }
 
 int ib_mad_enforce_security(struct ib_mad_agent_private *map, u16 pkey_index)