Date:   Wed, 22 Feb 2023 16:25:07 +0200
From:   Vladimir Oltean <olteanv@gmail.com>
To:     Kurt Kanzenbach <kurt@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sasha Levin <sashal@kernel.org>
Cc:     Vladimir Oltean <vladimir.oltean@nxp.com>, netdev@vger.kernel.org,
        Vinicius Costa Gomes <vinicius.gomes@intel.com>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Jiri Pirko <jiri@resnulli.us>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Voon Weifeng <weifeng.voon@intel.com>,
        linux-kernel@vger.kernel.org,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH v2 net 2/2] net/sched: taprio: make qdisc_leaf() see the
 per-netdev-queue pfifo child qdiscs
Message-ID: <20230222142507.hapqjfhswhlq42ay@skbuf>
References: <20220915100802.2308279-1-vladimir.oltean@nxp.com>
 <20220915100802.2308279-3-vladimir.oltean@nxp.com>
 <874jrdvluv.fsf@kurt>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <874jrdvluv.fsf@kurt>
Precedence: bulk

+Greg, Sasha.

Hi Kurt,

On Wed, Feb 22, 2023 at 03:03:04PM +0100, Kurt Kanzenbach wrote:
> This commit was backported to v5.15-LTS which results in NULL pointer
> dereferences e.g., when attaching an ETF child qdisc to taprio.
> 
> From what I can see is, that the issue was reported back then and this
> commit was reverted [1]. However, the revert didn't make it into
> v5.15-LTS? Is there a reason for it? I'm testing 5.15.94-rt59 here.
> 
> Thanks,
> Kurt
> 
> [1] - https://lore.kernel.org/all/20221004220100.1650558-1-vladimir.oltean@nxp.com/

You are right; the patchwork-bot clearly says that the revert was
applied to net.git as commit af7b29b1deaa ("Revert "net/sched: taprio:
make qdisc_leaf() see the per-netdev-queue pfifo child qdiscs""), but
the revert never made it to stable.

OTOH, the original patch did make it to, and still is in, linux-stable.
I have backport notification emails of the original to 5.4, 5.10, 5.15, 5.19.

Greg, Sasha, can you please pick up and backport commit af7b29b1deaa
("Revert "net/sched: taprio: make qdisc_leaf() see the per-netdev-queue
pfifo child qdiscs"") to the currently maintained stable kernels?

Thanks.