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: 5c5670fae4 ("net/sched: Introduce sample tc action")
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
