netdev - Re: [PATCH net 1/2] net/sched: cls_u32: fix netns refcount changes in u32

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Date:   Thu, 14 Apr 2022 11:59:01 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>, netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH net 1/2] net/sched: cls_u32: fix netns refcount changes in
 u32_change()

On 2022-04-13 13:35, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> We are now able to detect extra put_net() at the moment
> they happen, instead of much later in correct code paths.
> 
> u32_init_knode() / tcf_exts_init() populates the ->exts.net
> pointer, but as mentioned in tcf_exts_init(),
> the refcount on netns has not been elevated yet.
> 
> The refcount is taken only once tcf_exts_get_net()
> is called.
> 
> So the two u32_destroy_key() calls from u32_change()
> are attempting to release an invalid reference on the netns.
> 

Looks good to me.

Acked-by: Jamal Hadi Salim <jhs@...atatu.com>

cheers,
jamal