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Date:   Mon, 21 Jun 2021 15:41:19 -0700
From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     syzbot <syzbot+7b2b13f4943374609532@syzkaller.appspotmail.com>
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Subject: Re: [syzbot] KASAN: use-after-free Read in
 check_all_holdout_tasks_trace
Message-ID: <20210621224119.GW4397@paulmck-ThinkPad-P17-Gen-1>
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On Sat, Jun 19, 2021 at 09:54:06AM -0700, syzbot wrote:
> syzbot has bisected this issue to:
> 
> commit f9006acc8dfe59e25aa75729728ac57a8d84fc32
> Author: Florian Westphal <fw@strlen.de>
> Date:   Wed Apr 21 07:51:08 2021 +0000
> 
>     netfilter: arp_tables: pass table pointer via nf_hook_ops
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10dceae8300000
> start commit:   0c38740c selftests/bpf: Fix ringbuf test fetching map FD
> git tree:       bpf-next
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=12dceae8300000
> console output: https://syzkaller.appspot.com/x/log.txt?x=14dceae8300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a6380da8984033f1
> dashboard link: https://syzkaller.appspot.com/bug?extid=7b2b13f4943374609532
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1264c2d7d00000
> 
> Reported-by: syzbot+7b2b13f4943374609532@syzkaller.appspotmail.com
> Fixes: f9006acc8dfe ("netfilter: arp_tables: pass table pointer via nf_hook_ops")
> 
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

I am not seeing any mention of check_all_holdout_tasks_trace() in
the console output, but I again suggest the following two patches:

6a04a59eacbd ("rcu-tasks: Don't delete holdouts within trc_inspect_reader()"
dd5da0a9140e ("rcu-tasks: Don't delete holdouts within trc_wait_for_one_reader()")

							Thanx, Paul