From: Vlad Buslov <vlad@buslov.dev>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Cong Wang <xiyou.wangcong@gmail.com>,
netdev@vger.kernel.org,
syzbot+80e32b5d1f9923f8ace6@syzkaller.appspotmail.com,
Jamal Hadi Salim <jhs@mojatatu.com>,
Vlad Buslov <vladbu@mellanox.com>, Jiri Pirko <jiri@resnulli.us>
Subject: Re: [Patch net] act_ife: load meta modules before tcf_idr_check_alloc()
Date: Mon, 07 Sep 2020 15:13:19 +0300 [thread overview]
Message-ID: <877dt5bx9c.fsf@buslov.dev> (raw)
In-Reply-To: <20200904221419.59ba1125@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
On Sat 05 Sep 2020 at 08:14, Jakub Kicinski <kuba@kernel.org> wrote:
> On Thu, 3 Sep 2020 19:10:11 -0700 Cong Wang wrote:
>> The following deadlock scenario is triggered by syzbot:
>>
>> Thread A: Thread B:
>> tcf_idr_check_alloc()
>> ...
>> populate_metalist()
>> rtnl_unlock()
>> rtnl_lock()
>> ...
>> request_module() tcf_idr_check_alloc()
>> rtnl_lock()
>>
>> At this point, thread A is waiting for thread B to release RTNL
>> lock, while thread B is waiting for thread A to commit the IDR
>> change with tcf_idr_insert() later.
>>
>> Break this deadlock situation by preloading ife modules earlier,
>> before tcf_idr_check_alloc(), this is fine because we only need
>> to load modules we need potentially.
>>
>> Reported-and-tested-by: syzbot+80e32b5d1f9923f8ace6@syzkaller.appspotmail.com
>> Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action")
>> Cc: Jamal Hadi Salim <jhs@mojatatu.com>
>> Cc: Vlad Buslov <vladbu@mellanox.com>
>
> Vlad, it'd have been nice to see your review tag here.
Reviewed. Sorry for the delay.
>
>> Cc: Jiri Pirko <jiri@resnulli.us>
>> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
>
> LGTM, applied and queued for stable, thank you Cong!
next prev parent reply other threads:[~2020-09-07 17:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 2:10 [Patch net] act_ife: load meta modules before tcf_idr_check_alloc() Cong Wang
2020-09-05 5:14 ` Jakub Kicinski
2020-09-07 12:13 ` Vlad Buslov [this message]
2020-09-07 12:12 ` Vlad Buslov
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