lkml.org 
[lkml]   [2020]   [Jul]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: 回复: INFO: rcu detected stall in tc modify qd isc
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)?

\
 
 \ /
  Last update: 2020-07-30 07:59    [W:0.064 / U:8.596 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site