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From: Dexuan Cui <decui@microsoft.com>
To: kimbrownkd <kimbrownkd@gmail.com>,
	Michael Kelley <mikelley@microsoft.com>,
	Long Li <longli@microsoft.com>,
	Sasha Levin <Alexander.Levin@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>
Cc: 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 03:46:48 +0000	[thread overview]
Message-ID: <PU1P153MB0169EB8CFC0A69407A8AE2C2BF980@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20190122020759.GA4054@ubu-Virtual-Machine>

> 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

  reply	other threads:[~2019-01-22  3:48 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 [this message]
2019-01-22  6:42   ` Kimberly Brown
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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