netdev - Re: [PATCH net] cls_matchall: avoid panic when receiving a packet before filter set

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Message-ID: <CAM_iQpXB83o+Nnbef8-h_8cg6rTVZn194uZvP1-VKPcJ+xMEjA@mail.gmail.com>
Date:   Tue, 30 Apr 2019 14:24:51 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Matteo Croce <mcroce@...hat.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net] cls_matchall: avoid panic when receiving a packet
 before filter set

On Mon, Apr 29, 2019 at 10:38 AM Matteo Croce <mcroce@...hat.com> wrote:
>
> When a matchall classifier is added, there is a small time interval in
> which tp->root is NULL. If we receive a packet in this small time slice
> a NULL pointer dereference will happen, leading to a kernel panic:

Hmm, why not just check tp->root against NULL in mall_classify()?

Also, which is the offending commit here? Please add a Fixes: tag.

Thanks.