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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/include/net/psample.h b/include/net/psample.h
index 37a4df23..6b578ce 100644
--- a/include/net/psample.h
+++ b/include/net/psample.h
@@ -11,6 +11,7 @@ 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);
