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Date:   Mon, 17 Apr 2023 16:00:11 -0700
From:   Peilin Ye <yepeilin.cs@gmail.com>
To:     Jamal Hadi Salim <jhs@mojatatu.com>
Cc:     Pedro Tammela <pctammela@mojatatu.com>,
        Seth Forshee <sforshee@digitalocean.com>,
        Jakub Kicinski <kuba@kernel.org>,
        syzbot <syzbot+b53a9c0d1ea4ad62da8b@syzkaller.appspotmail.com>,
        davem@davemloft.net, edumazet@google.com, jiri@resnulli.us,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        pabeni@redhat.com, syzkaller-bugs@googlegroups.com,
        xiyou.wangcong@gmail.com, peilin.ye@bytedance.com
Subject: Re: [syzbot] [net?] KASAN: slab-use-after-free Write in
 mini_qdisc_pair_swap
Message-ID: <20230417230011.GA41709@bytedance>
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Hi all,

On Mon, Apr 03, 2023 at 11:58:44AM -0400, Jamal Hadi Salim wrote:
> To provide more update:
> Happens on single processor before Seth's patches; and only on
> multi-processor after Seth's patches.
> Theory is: there is a logic bug in the miniqdisc rcu visibility. Feels
> like the freeing of the structure is done without rcu involvement.
> Jiri/Cong maybe you can take a look since youve been dabbling in
> miniqdisc? The reproducer worked for me and Pedro 100% of the time.

I also reproduced this UAF using the syzkaller reproducer in the report
(the C reproducer did not work for me for unknown reasons).  I will look
into this.

Thanks,
Peilin Ye