4.7-stable review patch. If anyone has any objections, please let me know.
------------------ From: Johannes Weiner <[email protected]> commit d979a39d7242e0601bf9b60e89628fb8ac577179 upstream. 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: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Johannes Weiner <[email protected]> Acked-by: Tejun Heo <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Vladimir Davydov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/cgroup.c | 6 ++++++ net/core/sock.c | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-) --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -6240,6 +6240,12 @@ void cgroup_sk_alloc(struct sock_cgroup_ if (cgroup_sk_alloc_disabled) return; + /* Socket clone path */ + if (skcd->val) { + cgroup_get(sock_cgroup_ptr(skcd)); + return; + } + rcu_read_lock(); while (true) { --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1362,7 +1362,6 @@ static struct sock *sk_prot_alloc(struct 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, i 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 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)
