Re: [PATCH net v4] cls_u32: fix use after free in u32_destroy_key()

On Mon, Feb 5, 2018 at 1:23 PM, Paolo Abeni [off-list ref] wrote:

The problem is that the htnode is freed before the linked knodes and the
latter will try to access the first at u32_destroy_key() time.
This change addresses the issue using the htnode refcnt to guarantee
the correct free order. While at it also add a RCU annotation,
to keep sparse happy.

v1 -> v2: use rtnl_derefence() instead of RCU read locks
v2 -> v3:
  - don't check refcnt in u32_destroy_hnode()
  - cleaned-up u32_destroy() implementation
  - cleaned-up code comment
v3 -> v4:
  - dropped unneeded comment

Reported-by: Li Shuang <redacted>
Fixes: c0d378ef1266 ("net_sched: use tcf_queue_work() in u32 filter")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Acked-by: Cong Wang <redacted>

Thanks.