From 9f1c2674b328a69ab5a9b5a1c52405795ee4163f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 8 Oct 2017 21:44:51 -0700 Subject: net: memcontrol: defer call to mem_cgroup_sk_alloc() Instead of calling mem_cgroup_sk_alloc() from BH context, it is better to call it from inet_csk_accept() in process context. Not only this removes code in mem_cgroup_sk_alloc(), but it also fixes a bug since listener might have been dismantled and css_get() might cause a use-after-free. Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets") Signed-off-by: Eric Dumazet Cc: Johannes Weiner Cc: Tejun Heo Signed-off-by: David S. Miller --- mm/memcontrol.c | 15 --------------- 1 file changed, 15 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d5f3a62887cf..661f046ad318 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5828,21 +5828,6 @@ void mem_cgroup_sk_alloc(struct sock *sk) if (!mem_cgroup_sockets_enabled) return; - /* - * Socket cloning can throw us here with sk_memcg already - * filled. It won't however, necessarily happen from - * process context. So the test for root memcg given - * the current task's memcg won't help us in this case. - * - * Respecting the original socket's memcg is a better - * decision in this case. - */ - if (sk->sk_memcg) { - BUG_ON(mem_cgroup_is_root(sk->sk_memcg)); - css_get(&sk->sk_memcg->css); - return; - } - rcu_read_lock(); memcg = mem_cgroup_from_task(current); if (memcg == root_mem_cgroup) -- cgit v1.2.3-58-ga151