From: Kimberly Brown <kimbrownkd@gmail.com>
To: Dexuan Cui <decui@microsoft.com>
Cc: Michael Kelley <mikelley@microsoft.com>,
Long Li <longli@microsoft.com>,
Sasha Levin <Alexander.Levin@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
"devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Drivers: hv: vmbus: Add mutex lock to channel show functions
Date: Tue, 22 Jan 2019 01:42:46 -0500 [thread overview]
Message-ID: <20190122064246.GA28613@ubu-Virtual-Machine> (raw)
In-Reply-To: <PU1P153MB0169EB8CFC0A69407A8AE2C2BF980@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM>
On Tue, Jan 22, 2019 at 03:46:48AM +0000, Dexuan Cui wrote:
> > From: Kimberly Brown <kimbrownkd@gmail.com>
> > Sent: Monday, January 21, 2019 6:08 PM
> > Subject: [PATCH] Drivers: hv: vmbus: Add mutex lock to channel show functions
> >
> > The channel level "_show" functions are vulnerable to race conditions.
> > Add a mutex lock and unlock around the call to the channel level "_show"
> > functions in vmbus_chan_attr_show().
> >
> > This problem was discussed here:
> > https://lkml.org/lkml/2018/10/18/830
> >
> > --- a/drivers/hv/vmbus_drv.c
> > +++ b/drivers/hv/vmbus_drv.c
> > @@ -1414,6 +1414,7 @@ static ssize_t vmbus_chan_attr_show(struct kobject
> > *kobj,
> > = container_of(attr, struct vmbus_chan_attribute, attr);
> > const struct vmbus_channel *chan
> > = container_of(kobj, struct vmbus_channel, kobj);
> > + ssize_t ret;
> >
> > if (!attribute->show)
> > return -EIO;
> > @@ -1421,7 +1422,10 @@ static ssize_t vmbus_chan_attr_show(struct
> > kobject *kobj,
> > if (chan->state != CHANNEL_OPENED_STATE)
> > return -EINVAL;
> >
> > - return attribute->show(chan, buf);
> > + mutex_lock(&vmbus_connection.channel_mutex);
> > + ret = attribute->show(chan, buf);
> > + mutex_unlock(&vmbus_connection.channel_mutex);
> > + return ret;
> > }
>
> It looks this patch is already able to fix the original issue:
> 6712cc9c2211 ("vmbus: don't return values for uninitalized channels"),
> as chan->state can't be CHANNEL_OPENED_STATE when
> channel->ringbuffer_page is not set up yet, or has been freed.
>
> Thanks,
> -- Dexuan
I think that patch 6712cc9c2211 fixes the problem when the channel is
not set up yet, but it doesn't fix the problem when the channel is being
closed. The channel could be freed after the check that "chan->state" is
CHANNEL_OPENED_STATE, while the "attribute->show()" function is running.
Actually, there should be checks that "chan" is not null and that
"chan->state" is CHANNEL_OPENED_STATE within the locked section. I'll
need to fix that.
next prev parent reply other threads:[~2019-01-22 6:42 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-22 2:07 [PATCH] Drivers: hv: vmbus: Add mutex lock to channel show functions Kimberly Brown
2019-01-22 3:46 ` Dexuan Cui
2019-01-22 6:42 ` Kimberly Brown [this message]
2019-01-22 18:40 ` Dexuan Cui
2019-01-28 19:58 ` Kimberly Brown
2019-01-29 19:20 ` Dexuan Cui
2019-01-31 15:19 ` Sasha Levin
2019-01-31 16:45 ` Michael Kelley
2019-01-31 17:47 ` Kimberly Brown
2019-02-01 14:13 ` Sasha Levin
2019-02-01 18:24 ` Dexuan Cui
2019-02-02 20:07 ` Kimberly Brown
2019-02-15 1:54 ` Sasha Levin
2019-02-15 2:27 ` Kimberly Brown
2019-02-22 3:46 ` [PATCH v2 0/2] Fix a race condition vulnerability in "_show" functions Kimberly Brown
2019-02-22 3:47 ` [PATCH v2 1/2] Drivers: hv: vmbus: Refactor chan->state if statement Kimberly Brown
2019-02-24 16:54 ` Michael Kelley
2019-02-22 3:47 ` [PATCH v2 2/2] Drivers: hv: vmbus: Add a channel ring buffer mutex lock Kimberly Brown
2019-02-24 16:53 ` Michael Kelley
2019-02-26 6:24 ` Kimberly Brown
2019-03-14 20:04 ` [PATCH v3 0/3] Drivers: hv: vmbus: Fix a race condition in "_show" functions Kimberly Brown
2019-03-14 20:05 ` [PATCH v3 1/3] Drivers: hv: vmbus: Refactor chan->state if statement Kimberly Brown
2019-03-14 20:05 ` [PATCH v3 2/3] Drivers: hv: vmbus: Set ring_info field to 0 and remove memset Kimberly Brown
2019-03-29 16:01 ` Michael Kelley
2019-03-14 20:05 ` [PATCH v3 3/3] Drivers: hv: vmbus: Fix race condition with new ring_buffer_info mutex Kimberly Brown
2019-03-14 22:45 ` Stephen Hemminger
2019-03-17 1:49 ` Kimberly Brown
2019-03-20 20:06 ` Stephen Hemminger
2019-03-21 3:47 ` Kimberly Brown
2019-03-21 16:04 ` Michael Kelley
2019-03-28 4:30 ` Kimberly Brown
2019-03-28 18:42 ` Stephen Hemminger
2019-03-29 16:04 ` Michael Kelley
2019-04-10 22:59 ` [PATCH v3 0/3] Drivers: hv: vmbus: Fix a race condition in "_show" functions Sasha Levin
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