Messages in this thread | | | From | Vinicius Costa Gomes <> | Subject | Re: 回复: INFO: rcu detected stall in tc_modify_qdisc | Date | Wed, 29 Jul 2020 12:13:25 -0700 |
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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.
Cheers, -- Vinicius
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