From 47cd2e188b643d49dce9aa805e896866e6936b50 Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Tue, 27 Aug 2019 21:49:38 +0300 Subject: [PATCH] net: sched: act_sample: fix psample group handling on overwrite [ Upstream commit dbf47a2a094edf58983265e323ca4bdcdb58b5ee ] 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 Signed-off-by: Greg Kroah-Hartman --- include/net/psample.h | 1 + net/psample/psample.c | 2 +- net/sched/act_sample.c | 5 ++++- 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/include/net/psample.h b/include/net/psample.h index 9b80f814ab04..94cb37a7bf75 100644 --- a/include/net/psample.h +++ b/include/net/psample.h @@ -12,6 +12,7 @@ struct psample_group { u32 group_num; u32 refcount; u32 seq; + struct rcu_head rcu; }; struct psample_group *psample_group_get(struct net *net, u32 group_num); diff --git a/net/psample/psample.c b/net/psample/psample.c index 64f95624f219..4cea353221da 100644 --- a/net/psample/psample.c +++ b/net/psample/psample.c @@ -156,7 +156,7 @@ static void psample_group_destroy(struct psample_group *group) { psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP); list_del(&group->list); - kfree(group); + kfree_rcu(group, rcu); } static struct psample_group * diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c index 12748a01533c..489db1064d5b 100644 --- a/net/sched/act_sample.c +++ b/net/sched/act_sample.c @@ -92,13 +92,16 @@ static int tcf_sample_init(struct net *net, struct nlattr *nla, tcf_idr_release(*a, bind); return -ENOMEM; } - 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]); } + if (psample_group) + psample_group_put(psample_group); if (ret == ACT_P_CREATED) tcf_idr_insert(tn, *a); return ret; -- 2.20.1