netdev - Re: [PATCH 3/5] net: sched: taprio: Fix null pointer deref bug

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Message-ID: <CAM_iQpUumzvJy3YJMAohwH=E=u=Urb=j4r=M+pWW3gaN5-4vgg@mail.gmail.com>
Date:   Mon, 22 Apr 2019 11:04:29 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Andre Guedes <andre.guedes@...el.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Vinicius Costa Gomes <vinicius.gomes@...el.com>
Subject: Re: [PATCH 3/5] net: sched: taprio: Fix null pointer deref bug

On Fri, Apr 19, 2019 at 6:06 PM Andre Guedes <andre.guedes@...el.com> wrote:
>
> If 'entry' is NULL we WARN_ON() but dereference the pointer anyway,
> generating a null pointer dereference bug. This patch fixes should_
> restart_cycle() so we return if the pointer is NULL.

Hmm, while you are on it, how is it possible to have entry==NULL
for should_restart_cycle(). It is only called in advance_sched()
where entry is already checked against NULL right before it,
so for me, entry is always NULL at the point of calling
should_restart_cycle().

Am I missing anything?

Thanks.