From dbf47a2a094edf58983265e323ca4bdcdb58b5ee Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Tue, 27 Aug 2019 21:49:38 +0300 Subject: net: sched: act_sample: fix psample group handling on overwrite Action sample doesn't properly handle psample_group pointer in overwrite case. Following issues need to be fixed: - In tcf_sample_init() function RCU_INIT_POINTER() is used to set s->psample_group, even though we neither setting the pointer to NULL, nor preventing concurrent readers from accessing the pointer in some way. Use rcu_swap_protected() instead to safely reset the pointer. - Old value of s->psample_group is not released or deallocated in any way, which results resource leak. Use psample_group_put() on non-NULL value obtained with rcu_swap_protected(). - The function psample_group_put() that released reference to struct psample_group pointed by rcu-pointer s->psample_group doesn't respect rcu grace period when deallocating it. Extend struct psample_group with rcu head and use kfree_rcu when freeing it. Fixes: 5c5670fae430 ("net/sched: Introduce sample tc action") Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller --- net/sched/act_sample.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'net/sched/act_sample.c') diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c index 7eff363f9f03..10229124a992 100644 --- a/net/sched/act_sample.c +++ b/net/sched/act_sample.c @@ -102,13 +102,17 @@ static int tcf_sample_init(struct net *net, struct nlattr *nla, goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); s->rate = rate; s->psample_group_num = psample_group_num; - RCU_INIT_POINTER(s->psample_group, psample_group); + rcu_swap_protected(s->psample_group, psample_group, + lockdep_is_held(&s->tcf_lock)); if (tb[TCA_SAMPLE_TRUNC_SIZE]) { s->truncate = true; s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]); } spin_unlock_bh(&s->tcf_lock); + + if (psample_group) + psample_group_put(psample_group); if (goto_ch) tcf_chain_put_by_act(goto_ch); -- cgit v1.2.3-59-g8ed1b