cgroup: duplicate cgroup reference when cloning sockets (d979a39d) · Commits · 戴 / test

When a socket is cloned, the associated sock_cgroup_data is duplicated but not its reference on the cgroup. As a result, the cgroup reference count will underflow when both sockets are destroyed later on. Fixes: ("sock, cgroup: add sock->sk_cgroup") Link: http://lkml.kernel.org/r/20160914194846.11153-2-hannes@cmpxchg.org Signed-off-by:

Johannes Weiner <hannes@cmpxchg.org> Acked-by:

Tejun Heo <tj@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

kernel/cgroup.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -6270,6 +6270,12 @@ void cgroup_sk_alloc(struct sock_cgroup_data *skcd)
		if (cgroup_sk_alloc_disabled)
		return;

		/* Socket clone path */
		if (skcd->val) {
		cgroup_get(sock_cgroup_ptr(skcd));
		return;
		}

		rcu_read_lock();

		while (true) {

net/core/sock.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1362,7 +1362,6 @@ static struct sock sk_prot_alloc(struct proto prot, gfp_t priority,
		if (!try_module_get(prot->owner))
		goto out_free_sec;
		sk_tx_queue_clear(sk);
		cgroup_sk_alloc(&sk->sk_cgrp_data);
		}

		return sk;
		@@ -1422,6 +1421,7 @@ struct sock sk_alloc(struct net net, int family, gfp_t priority,
		sock_net_set(sk, net);
		atomic_set(&sk->sk_wmem_alloc, 1);

		cgroup_sk_alloc(&sk->sk_cgrp_data);
		sock_update_classid(&sk->sk_cgrp_data);
		sock_update_netprioidx(&sk->sk_cgrp_data);
		}
		@@ -1566,6 +1566,9 @@ struct sock sk_clone_lock(const struct sock sk, const gfp_t priority)
		newsk->sk_priority = 0;
		newsk->sk_incoming_cpu = raw_smp_processor_id();
		atomic64_set(&newsk->sk_cookie, 0);

		cgroup_sk_alloc(&newsk->sk_cgrp_data);

		/*
		* Before updating sk_refcnt, we must commit prior changes to memory
		* (Documentation/RCU/rculist_nulls.txt for details)

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