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Groups > linux.kernel > #1705490 > unrolled thread

[PATCH] devfreq: add error check for sscanf in userspace governor

Started bySantosh Mardi <gsantosh@codeaurora.org>
First post2017-08-07 15:10 +0200
Last post2017-08-08 21:30 +0200
Articles 5 — 5 participants

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  [PATCH] devfreq: add error check for sscanf in userspace governor Santosh Mardi <gsantosh@codeaurora.org> - 2017-08-07 15:10 +0200
    RE: [PATCH] devfreq: add error check for sscanf in userspace  governor MyungJoo Ham <myungjoo.ham@samsung.com> - 2017-08-08 02:20 +0200
    Re: [PATCH] devfreq: add error check for sscanf in userspace  governor Chanwoo Choi <cw00.choi@samsung.com> - 2017-08-08 03:00 +0200
    Re: [PATCH] devfreq: add error check for sscanf in userspace governor Pavan Kondeti <pkondeti@codeaurora.org> - 2017-08-08 09:00 +0200
      Re: [PATCH] devfreq: add error check for sscanf in userspace governor Saravana Kannan <skannan@codeaurora.org> - 2017-08-08 21:30 +0200

#1705490 — [PATCH] devfreq: add error check for sscanf in userspace governor

FromSantosh Mardi <gsantosh@codeaurora.org>
Date2017-08-07 15:10 +0200
Subject[PATCH] devfreq: add error check for sscanf in userspace governor
Message-ID<ubPXd-bV-43@gated-at.bofh.it>
store_freq function of devfreq userspace governor
executes further, even if error is returned from sscanf,
this will result in setting up wrong frequency value.

Add proper error check to bail out if any error is returned.

Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>
---
 drivers/devfreq/governor_userspace.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
index 77028c2..1d0c9cc 100644
--- a/drivers/devfreq/governor_userspace.c
+++ b/drivers/devfreq/governor_userspace.c
@@ -53,12 +53,15 @@ static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
 	mutex_lock(&devfreq->lock);
 	data = devfreq->data;
 
-	sscanf(buf, "%lu", &wanted);
+	err = sscanf(buf, "%lu", &wanted);
+	if (err != 1)
+		goto out;
 	data->user_frequency = wanted;
 	data->valid = true;
 	err = update_devfreq(devfreq);
 	if (err == 0)
 		err = count;
+out:
 	mutex_unlock(&devfreq->lock);
 	return err;
 }
-- 
1.9.1

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#1705930 — RE: [PATCH] devfreq: add error check for sscanf in userspace governor

FromMyungJoo Ham <myungjoo.ham@samsung.com>
Date2017-08-08 02:20 +0200
SubjectRE: [PATCH] devfreq: add error check for sscanf in userspace governor
Message-ID<uc0pB-7WI-13@gated-at.bofh.it>
In reply to#1705490
> store_freq function of devfreq userspace governor
> executes further, even if error is returned from sscanf,
> this will result in setting up wrong frequency value.
> 
> Add proper error check to bail out if any error is returned.
> 
> Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>

Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>

> ---
>  drivers/devfreq/governor_userspace.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

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#1705933 — Re: [PATCH] devfreq: add error check for sscanf in userspace governor

FromChanwoo Choi <cw00.choi@samsung.com>
Date2017-08-08 03:00 +0200
SubjectRe: [PATCH] devfreq: add error check for sscanf in userspace governor
Message-ID<uc12h-8bw-9@gated-at.bofh.it>
In reply to#1705490
Hi,

On 2017년 08월 07일 22:06, Santosh Mardi wrote:
> store_freq function of devfreq userspace governor
> executes further, even if error is returned from sscanf,
> this will result in setting up wrong frequency value.
> 
> Add proper error check to bail out if any error is returned.
> 
> Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>
> ---
>  drivers/devfreq/governor_userspace.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
> index 77028c2..1d0c9cc 100644
> --- a/drivers/devfreq/governor_userspace.c
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -53,12 +53,15 @@ static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
>  	mutex_lock(&devfreq->lock);
>  	data = devfreq->data;
>  
> -	sscanf(buf, "%lu", &wanted);
> +	err = sscanf(buf, "%lu", &wanted);
> +	if (err != 1)
> +		goto out;
>  	data->user_frequency = wanted;
>  	data->valid = true;
>  	err = update_devfreq(devfreq);
>  	if (err == 0)
>  		err = count;
> +out:
>  	mutex_unlock(&devfreq->lock);
>  	return err;
>  }
> 

Looks good to me.
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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#1706079

FromPavan Kondeti <pkondeti@codeaurora.org>
Date2017-08-08 09:00 +0200
Message-ID<uc6EH-4gz-25@gated-at.bofh.it>
In reply to#1705490
Hi Santosh,

On Mon, Aug 7, 2017 at 6:36 PM, Santosh Mardi <gsantosh@codeaurora.org> wrote:
> store_freq function of devfreq userspace governor
> executes further, even if error is returned from sscanf,
> this will result in setting up wrong frequency value.
>
> Add proper error check to bail out if any error is returned.
>
> Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>
> ---
>  drivers/devfreq/governor_userspace.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
> index 77028c2..1d0c9cc 100644
> --- a/drivers/devfreq/governor_userspace.c
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -53,12 +53,15 @@ static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
>         mutex_lock(&devfreq->lock);
>         data = devfreq->data;
>
> -       sscanf(buf, "%lu", &wanted);
> +       err = sscanf(buf, "%lu", &wanted);
> +       if (err != 1)
> +               goto out;

You can save this goto statement by moving this sscanf checking to
before taking the mutex.

>         data->user_frequency = wanted;
>         data->valid = true;
>         err = update_devfreq(devfreq);
>         if (err == 0)
>                 err = count;
> +out:
>         mutex_unlock(&devfreq->lock);
>         return err;
>  }
> --
> 1.9.1
>


-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
Linux Foundation Collaborative Project

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#1706844

FromSaravana Kannan <skannan@codeaurora.org>
Date2017-08-08 21:30 +0200
Message-ID<ucimt-4kC-15@gated-at.bofh.it>
In reply to#1706079
On 08/07/2017 11:56 PM, Pavan Kondeti wrote:
> Hi Santosh,
>
> On Mon, Aug 7, 2017 at 6:36 PM, Santosh Mardi <gsantosh@codeaurora.org> wrote:
>> store_freq function of devfreq userspace governor
>> executes further, even if error is returned from sscanf,
>> this will result in setting up wrong frequency value.
>>
>> Add proper error check to bail out if any error is returned.
>>
>> Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>
>> ---
>>   drivers/devfreq/governor_userspace.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
>> index 77028c2..1d0c9cc 100644
>> --- a/drivers/devfreq/governor_userspace.c
>> +++ b/drivers/devfreq/governor_userspace.c
>> @@ -53,12 +53,15 @@ static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
>>          mutex_lock(&devfreq->lock);
>>          data = devfreq->data;
>>
>> -       sscanf(buf, "%lu", &wanted);
>> +       err = sscanf(buf, "%lu", &wanted);

Also, we could just use kstroul().

>> +       if (err != 1)
>> +               goto out;
>
> You can save this goto statement by moving this sscanf checking to
> before taking the mutex.
>
>>          data->user_frequency = wanted;
>>          data->valid = true;
>>          err = update_devfreq(devfreq);
>>          if (err == 0)
>>                  err = count;
>> +out:
>>          mutex_unlock(&devfreq->lock);
>>          return err;
>>   }
>> --
>> 1.9.1
>>

-Saravana


-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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