From: Pavel Skripkin <paskripkin@gmail.com>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Yang Yingliang <yangyingliang@huawei.com>,
LKML <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>,
Xu Qiang <xuqiang36@huawei.com>
Subject: Re: [PATCH v3] workqueue: fix UAF in pwq_unbound_release_workfn()
Date: Fri, 16 Jul 2021 13:45:33 +0300 [thread overview]
Message-ID: <20210716134533.17e82d88@gmail.com> (raw)
In-Reply-To: <20210715215219.061a2f25@gmail.com>
On Thu, 15 Jul 2021 21:52:19 +0300
Pavel Skripkin <paskripkin@gmail.com> wrote:
> On Thu, 15 Jul 2021 16:08:12 +0800
> Lai Jiangshan <jiangshanlai@gmail.com> wrote:
>
> > On Wed, Jul 14, 2021 at 5:16 PM Yang Yingliang
> > <yangyingliang@huawei.com> wrote:
> >
> > >
> > > Fixes: 2d5f0764b526 ("workqueue: split apply_workqueue_attrs()
> > > into 3 stages") Reported-by: Hulk Robot <hulkci@huawei.com>
> > > Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com>
> > > Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> > > ---
> > > v3:
> > > drop the v2 and v1 changes, add check pwq in
> > > pwq_unbound_release_workfn() v2:
> > > also use free_wqattrs_ctx() in workqueue_apply_unbound_cpumask()
> > > ---
> > > kernel/workqueue.c | 20 +++++++++++++-------
> > > 1 file changed, 13 insertions(+), 7 deletions(-)
> > >
> >
> > I'm fine with the code.
> >
> > Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
> >
> > Hello, Pavel
> >
> > Could you have a test again, please?
> >
>
> Hi, Lai!
>
> Sorry for late response.
>
> Yes, I have started local syzkaller instance just now, so I will share
> the results tomorrow.
>
Hi, everyone!
With this patch applied my local syzbot instance didn't hit any of the
reported bugs [1].
Tested-by: Pavel Skripkin <paskripkin@gmail.com>
Thank you!
[1] https://lore.kernel.org/lkml/20210708162417.777bff77@gmail.com/
With regards,
Pavel Skripkin
>
> > Thanks,
> > Lai
> >
> > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> > > index 50142fc08902..f148eacda55a 100644
> > > --- a/kernel/workqueue.c
> > > +++ b/kernel/workqueue.c
> > > @@ -3676,15 +3676,21 @@ static void
> > > pwq_unbound_release_workfn(struct work_struct *work)
> > > unbound_release_work); struct workqueue_struct *wq = pwq->wq;
> > > struct worker_pool *pool = pwq->pool;
> > > - bool is_last;
> > > + bool is_last = false;
> > >
> > > - if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
> > > - return;
> > > + /*
> > > + * when @pwq is not linked, it doesn't hold any reference
> > > to the
> > > + * @wq, and @wq is invalid to access.
> > > + */
> > > + if (!list_empty(&pwq->pwqs_node)) {
> > > + if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
> > > + return;
> > >
> > > - mutex_lock(&wq->mutex);
> > > - list_del_rcu(&pwq->pwqs_node);
> > > - is_last = list_empty(&wq->pwqs);
> > > - mutex_unlock(&wq->mutex);
> > > + mutex_lock(&wq->mutex);
> > > + list_del_rcu(&pwq->pwqs_node);
> > > + is_last = list_empty(&wq->pwqs);
> > > + mutex_unlock(&wq->mutex);
> > > + }
> > >
> > > mutex_lock(&wq_pool_mutex);
> > > put_unbound_pool(pool);
> > > --
> > > 2.25.1
> > >
>
>
> With regards,
> Pavel Skripkin
>
next prev parent reply other threads:[~2021-07-16 10:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 9:19 [PATCH v3] workqueue: fix UAF in pwq_unbound_release_workfn() Yang Yingliang
2021-07-15 8:08 ` Lai Jiangshan
2021-07-15 18:52 ` Pavel Skripkin
2021-07-16 10:45 ` Pavel Skripkin [this message]
2021-07-16 16:14 ` Tejun Heo
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