netdev - Re: [PATCH net v4] cls_u32: fix use after free in u32_destroy

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Message-ID: <CAM_iQpUTR3+of29EGyoJg3ty+z9NEZ2WrmrHmcXtOfjkhVmmzw@mail.gmail.com>
Date:   Mon, 5 Feb 2018 13:37:54 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>, Li Shuang <shuali@...hat.com>,
        Ivan Vecera <ivecera@...hat.com>
Subject: 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 <pabeni@...hat.com> 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 <shuali@...hat.com>
> Fixes: c0d378ef1266 ("net_sched: use tcf_queue_work() in u32 filter")
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>

Acked-by: Cong Wang <xiyou.wangcong@...il.com>

Thanks.