From: Dmitry Vyukov <dvyukov@google.com>
To: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Cc: "Zhang, Qiang" <Qiang.Zhang@windriver.com>,
syzbot <syzbot+9f78d5c664a8c33f4cce@syzkaller.appspotmail.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"fweisbec@gmail.com" <fweisbec@gmail.com>,
"jhs@mojatatu.com" <jhs@mojatatu.com>,
"jiri@resnulli.us" <jiri@resnulli.us>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"syzkaller-bugs@googlegroups.com"
<syzkaller-bugs@googlegroups.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"xiyou.wangcong@gmail.com" <xiyou.wangcong@gmail.com>
Subject: Re: 回复: INFO: rcu detected stall in tc_modify_qdisc
Date: Thu, 30 Jul 2020 07:58:16 +0200 [thread overview]
Message-ID: <CACT4Y+ZMvaJMiXikYCm-Xym8ddKDY0n-5=kwH7i2Hu-9uJW1kQ@mail.gmail.com> (raw)
In-Reply-To: <87tuxqxhgq.fsf@intel.com>
On Wed, Jul 29, 2020 at 9:13 PM Vinicius Costa Gomes
<vinicius.gomes@intel.com> wrote:
>
> Hi,
>
> "Zhang, Qiang" <Qiang.Zhang@windriver.com> writes:
>
> > ________________________________________
> > 发件人: linux-kernel-owner@vger.kernel.org <linux-kernel-owner@vger.kernel.org> 代表 syzbot <syzbot+9f78d5c664a8c33f4cce@syzkaller.appspotmail.com>
> > 发送时间: 2020年7月29日 13:53
> > 收件人: davem@davemloft.net; fweisbec@gmail.com; jhs@mojatatu.com; jiri@resnulli.us; linux-kernel@vger.kernel.org; mingo@kernel.org; netdev@vger.kernel.org; syzkaller-bugs@googlegroups.com; tglx@linutronix.de; vinicius.gomes@intel.com; xiyou.wangcong@gmail.com
> > 主题: INFO: rcu detected stall in tc_modify_qdisc
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 181964e6 fix a braino in cmsghdr_from_user_compat_to_kern()
> > git tree: net
> > console output: https://syzkaller.appspot.com/x/log.txt?x=12925e38900000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=f87a5e4232fdb267
> > dashboard link: https://syzkaller.appspot.com/bug?extid=9f78d5c664a8c33f4cce
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> > syz repro:
> > https://syzkaller.appspot.com/x/repro.syz?x=16587f8c900000
>
> It seems that syzkaller is generating an schedule with too small
> intervals (3ns in this case) which causes a hrtimer busy-loop which
> starves other kernel threads.
>
> We could put some limits on the interval when running in software mode,
> but I don't like this too much, because we are talking about users with
> CAP_NET_ADMIN and they have easier ways to do bad things to the system.
Hi Vinicius,
Could you explain why you don't like the argument if it's for CAP_NET_ADMIN?
Good code should check arguments regardless I think and it's useful to
protect root from, say, programming bugs rather than kill the machine
on any bug and misconfiguration. What am I missing?
Also are we talking about CAP_NET_ADMIN in a user ns as well
(effectively nobody)?
next prev parent reply other threads:[~2020-07-30 5:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-29 5:53 INFO: rcu detected stall in tc_modify_qdisc syzbot
2020-07-29 7:28 ` 回复: " Zhang, Qiang
2020-07-29 19:13 ` Vinicius Costa Gomes
2020-07-30 5:58 ` Dmitry Vyukov [this message]
2020-07-30 17:44 ` Vinicius Costa Gomes
2020-07-30 18:36 ` Eric Dumazet
2020-07-30 21:01 ` Vinicius Costa Gomes
2020-07-30 19:19 ` Dmitry Vyukov
2020-07-30 22:01 ` Vinicius Costa Gomes
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