* [PATCH] PM / devfreq: Check NULL governor in available_governors_show
@ 2019-09-23 16:34 ` Leonard Crestez
0 siblings, 0 replies; 10+ messages in thread
From: Leonard Crestez @ 2019-09-23 16:34 UTC (permalink / raw)
To: Matthias Kaehlcke, MyungJoo Ham, Kyungmin Park
Cc: Artur Świgoń, linux-pm, Krzysztof Kozlowski,
Lukasz Luba, Chanwoo Choi, linux-arm-kernel
The governor is initialized after sysfs attributes become visible so in
theory the governor field can be NULL here.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
---
drivers/devfreq/devfreq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Found this by hacking device core to call attribute "show" functions
from inside device_add.
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 00fc23fea5b2..896fb2312f2f 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
/*
* The devfreq with immutable governor (e.g., passive) shows
* only own governor.
*/
- if (df->governor->immutable) {
+ if (df->governor && df->governor->immutable) {
count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
"%s ", df->governor_name);
/*
* The devfreq device shows the registered governor except for
* immutable governors such as passive governor .
--
2.17.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
2019-09-23 16:34 ` Leonard Crestez
@ 2019-09-23 18:50 ` Matthias Kaehlcke
-1 siblings, 0 replies; 10+ messages in thread
From: Matthias Kaehlcke @ 2019-09-23 18:50 UTC (permalink / raw)
To: Leonard Crestez
Cc: MyungJoo Ham, Kyungmin Park, Chanwoo Choi, Artur Świgoń,
Krzysztof Kozlowski, Lukasz Luba, linux-pm, linux-arm-kernel
On Mon, Sep 23, 2019 at 07:34:43PM +0300, Leonard Crestez wrote:
> The governor is initialized after sysfs attributes become visible so in
> theory the governor field can be NULL here.
>
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> ---
> drivers/devfreq/devfreq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Found this by hacking device core to call attribute "show" functions
> from inside device_add.
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 00fc23fea5b2..896fb2312f2f 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>
> /*
> * The devfreq with immutable governor (e.g., passive) shows
> * only own governor.
> */
> - if (df->governor->immutable) {
> + if (df->governor && df->governor->immutable) {
> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
> "%s ", df->governor_name);
> /*
> * The devfreq device shows the registered governor except for
> * immutable governors such as passive governor .
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
@ 2019-09-23 18:50 ` Matthias Kaehlcke
0 siblings, 0 replies; 10+ messages in thread
From: Matthias Kaehlcke @ 2019-09-23 18:50 UTC (permalink / raw)
To: Leonard Crestez
Cc: Artur Świgoń, linux-pm, Krzysztof Kozlowski,
Lukasz Luba, Chanwoo Choi, Kyungmin Park, MyungJoo Ham,
linux-arm-kernel
On Mon, Sep 23, 2019 at 07:34:43PM +0300, Leonard Crestez wrote:
> The governor is initialized after sysfs attributes become visible so in
> theory the governor field can be NULL here.
>
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> ---
> drivers/devfreq/devfreq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Found this by hacking device core to call attribute "show" functions
> from inside device_add.
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 00fc23fea5b2..896fb2312f2f 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>
> /*
> * The devfreq with immutable governor (e.g., passive) shows
> * only own governor.
> */
> - if (df->governor->immutable) {
> + if (df->governor && df->governor->immutable) {
> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
> "%s ", df->governor_name);
> /*
> * The devfreq device shows the registered governor except for
> * immutable governors such as passive governor .
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
2019-09-23 16:34 ` Leonard Crestez
@ 2019-09-24 1:52 ` Chanwoo Choi
-1 siblings, 0 replies; 10+ messages in thread
From: Chanwoo Choi @ 2019-09-24 1:52 UTC (permalink / raw)
To: Leonard Crestez, Matthias Kaehlcke, MyungJoo Ham, Kyungmin Park
Cc: Artur Świgoń, Krzysztof Kozlowski, Lukasz Luba,
linux-pm, linux-arm-kernel
Hi,
On 19. 9. 24. 오전 1:34, Leonard Crestez wrote:
> The governor is initialized after sysfs attributes become visible so in
> theory the governor field can be NULL here.
>
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> ---
> drivers/devfreq/devfreq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Found this by hacking device core to call attribute "show" functions
> from inside device_add.
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 00fc23fea5b2..896fb2312f2f 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>
> /*
> * The devfreq with immutable governor (e.g., passive) shows
> * only own governor.
> */
> - if (df->governor->immutable) {
> + if (df->governor && df->governor->immutable) {
> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
> "%s ", df->governor_name);
> /*
> * The devfreq device shows the registered governor except for
> * immutable governors such as passive governor .
>
As you mentioned, it create sysfs and then initialize the governor instance
as following:
device_register()
device_add()
device_add_attrs()
creating sysfs entries.
governor = try_then_request_governor(...)
Thanks for fix-up.
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Additionally, you have to add the following 'fixes' tag
and then send it to stable mailing list(stable@vger.kernel.org).
- Fixes: bcf23c79c4e46 ("PM / devfreq: Fix available_governor sysfs")
--
Best Regards,
Chanwoo Choi
Samsung Electronics
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
@ 2019-09-24 1:52 ` Chanwoo Choi
0 siblings, 0 replies; 10+ messages in thread
From: Chanwoo Choi @ 2019-09-24 1:52 UTC (permalink / raw)
To: Leonard Crestez, Matthias Kaehlcke, MyungJoo Ham, Kyungmin Park
Cc: Artur Świgoń, linux-pm, linux-arm-kernel,
Krzysztof Kozlowski, Lukasz Luba
Hi,
On 19. 9. 24. 오전 1:34, Leonard Crestez wrote:
> The governor is initialized after sysfs attributes become visible so in
> theory the governor field can be NULL here.
>
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> ---
> drivers/devfreq/devfreq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Found this by hacking device core to call attribute "show" functions
> from inside device_add.
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 00fc23fea5b2..896fb2312f2f 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>
> /*
> * The devfreq with immutable governor (e.g., passive) shows
> * only own governor.
> */
> - if (df->governor->immutable) {
> + if (df->governor && df->governor->immutable) {
> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
> "%s ", df->governor_name);
> /*
> * The devfreq device shows the registered governor except for
> * immutable governors such as passive governor .
>
As you mentioned, it create sysfs and then initialize the governor instance
as following:
device_register()
device_add()
device_add_attrs()
creating sysfs entries.
governor = try_then_request_governor(...)
Thanks for fix-up.
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Additionally, you have to add the following 'fixes' tag
and then send it to stable mailing list(stable@vger.kernel.org).
- Fixes: bcf23c79c4e46 ("PM / devfreq: Fix available_governor sysfs")
--
Best Regards,
Chanwoo Choi
Samsung Electronics
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
2019-09-24 1:52 ` Chanwoo Choi
@ 2019-09-24 7:17 ` Leonard Crestez
-1 siblings, 0 replies; 10+ messages in thread
From: Leonard Crestez @ 2019-09-24 7:17 UTC (permalink / raw)
To: Chanwoo Choi, Matthias Kaehlcke, MyungJoo Ham, Kyungmin Park
Cc: Artur Świgoń, Krzysztof Kozlowski, Lukasz Luba,
linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
On 2019-09-24 4:48 AM, Chanwoo Choi wrote:
> On 19. 9. 24. 오전 1:34, Leonard Crestez wrote:
>> The governor is initialized after sysfs attributes become visible so in
>> theory the governor field can be NULL here.
>>
>> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
>> ---
>> drivers/devfreq/devfreq.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Found this by hacking device core to call attribute "show" functions
>> from inside device_add.
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 00fc23fea5b2..896fb2312f2f 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>>
>> /*
>> * The devfreq with immutable governor (e.g., passive) shows
>> * only own governor.
>> */
>> - if (df->governor->immutable) {
>> + if (df->governor && df->governor->immutable) {
>> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
>> "%s ", df->governor_name);
>> /*
>> * The devfreq device shows the registered governor except for
>> * immutable governors such as passive governor .
>>
>
> As you mentioned, it create sysfs and then initialize the governor instance
> as following:
>
> device_register()
> device_add()
> device_add_attrs()
> creating sysfs entries.
> governor = try_then_request_governor(...)
>
>
> Thanks for fix-up.
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>
> Additionally, you have to add the following 'fixes' tag
> and then send it to stable mailing list(stable@vger.kernel.org).
> - Fixes: bcf23c79c4e46 ("PM / devfreq: Fix available_governor sysfs")
OK, but I'm not sure this meets the criteria for inclusion into linux
stable:
* It must fix a real bug that bothers people (not a, "This could be a
problem..." type thing).
* No "theoretical race condition" issues, unless an explanation of how
the race can be exploited is also provided.
This patch fixes a theoretical race condition which has been there since
the start.
--
Regards,
Leonard
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
@ 2019-09-24 7:17 ` Leonard Crestez
0 siblings, 0 replies; 10+ messages in thread
From: Leonard Crestez @ 2019-09-24 7:17 UTC (permalink / raw)
To: Chanwoo Choi, Matthias Kaehlcke, MyungJoo Ham, Kyungmin Park
Cc: Artur Świgoń, linux-pm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, Krzysztof Kozlowski,
Lukasz Luba
On 2019-09-24 4:48 AM, Chanwoo Choi wrote:
> On 19. 9. 24. 오전 1:34, Leonard Crestez wrote:
>> The governor is initialized after sysfs attributes become visible so in
>> theory the governor field can be NULL here.
>>
>> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
>> ---
>> drivers/devfreq/devfreq.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Found this by hacking device core to call attribute "show" functions
>> from inside device_add.
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 00fc23fea5b2..896fb2312f2f 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>>
>> /*
>> * The devfreq with immutable governor (e.g., passive) shows
>> * only own governor.
>> */
>> - if (df->governor->immutable) {
>> + if (df->governor && df->governor->immutable) {
>> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
>> "%s ", df->governor_name);
>> /*
>> * The devfreq device shows the registered governor except for
>> * immutable governors such as passive governor .
>>
>
> As you mentioned, it create sysfs and then initialize the governor instance
> as following:
>
> device_register()
> device_add()
> device_add_attrs()
> creating sysfs entries.
> governor = try_then_request_governor(...)
>
>
> Thanks for fix-up.
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>
> Additionally, you have to add the following 'fixes' tag
> and then send it to stable mailing list(stable@vger.kernel.org).
> - Fixes: bcf23c79c4e46 ("PM / devfreq: Fix available_governor sysfs")
OK, but I'm not sure this meets the criteria for inclusion into linux
stable:
* It must fix a real bug that bothers people (not a, "This could be a
problem..." type thing).
* No "theoretical race condition" issues, unless an explanation of how
the race can be exploited is also provided.
This patch fixes a theoretical race condition which has been there since
the start.
--
Regards,
Leonard
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
2019-09-24 7:17 ` Leonard Crestez
@ 2019-09-24 7:25 ` Chanwoo Choi
-1 siblings, 0 replies; 10+ messages in thread
From: Chanwoo Choi @ 2019-09-24 7:25 UTC (permalink / raw)
To: Leonard Crestez, Matthias Kaehlcke, MyungJoo Ham, Kyungmin Park
Cc: Artur Świgoń, Krzysztof Kozlowski, Lukasz Luba,
linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
On 19. 9. 24. 오후 4:17, Leonard Crestez wrote:
> On 2019-09-24 4:48 AM, Chanwoo Choi wrote:
>> On 19. 9. 24. 오전 1:34, Leonard Crestez wrote:
>>> The governor is initialized after sysfs attributes become visible so in
>>> theory the governor field can be NULL here.
>>>
>>> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
>>> ---
>>> drivers/devfreq/devfreq.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> Found this by hacking device core to call attribute "show" functions
>>> from inside device_add.
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index 00fc23fea5b2..896fb2312f2f 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>>>
>>> /*
>>> * The devfreq with immutable governor (e.g., passive) shows
>>> * only own governor.
>>> */
>>> - if (df->governor->immutable) {
>>> + if (df->governor && df->governor->immutable) {
>>> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
>>> "%s ", df->governor_name);
>>> /*
>>> * The devfreq device shows the registered governor except for
>>> * immutable governors such as passive governor .
>>>
>>
>> As you mentioned, it create sysfs and then initialize the governor instance
>> as following:
>>
>> device_register()
>> device_add()
>> device_add_attrs()
>> creating sysfs entries.
>> governor = try_then_request_governor(...)
>>
>>
>> Thanks for fix-up.
>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>>
>> Additionally, you have to add the following 'fixes' tag
>> and then send it to stable mailing list(stable@vger.kernel.org).
>> - Fixes: bcf23c79c4e46 ("PM / devfreq: Fix available_governor sysfs")
>
> OK, but I'm not sure this meets the criteria for inclusion into linux
> stable:
>
> * It must fix a real bug that bothers people (not a, "This could be a
> problem..." type thing).
> * No "theoretical race condition" issues, unless an explanation of how
> the race can be exploited is also provided.
OK. If you think that it is not necessary to send it to stable mailing list,
don't send it. Thanks.
>
> This patch fixes a theoretical race condition which has been there since
> the start.
>
> --
> Regards,
> Leonard
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] PM / devfreq: Check NULL governor in available_governors_show
@ 2019-09-24 7:25 ` Chanwoo Choi
0 siblings, 0 replies; 10+ messages in thread
From: Chanwoo Choi @ 2019-09-24 7:25 UTC (permalink / raw)
To: Leonard Crestez, Matthias Kaehlcke, MyungJoo Ham, Kyungmin Park
Cc: Artur Świgoń, linux-pm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, Krzysztof Kozlowski,
Lukasz Luba
On 19. 9. 24. 오후 4:17, Leonard Crestez wrote:
> On 2019-09-24 4:48 AM, Chanwoo Choi wrote:
>> On 19. 9. 24. 오전 1:34, Leonard Crestez wrote:
>>> The governor is initialized after sysfs attributes become visible so in
>>> theory the governor field can be NULL here.
>>>
>>> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
>>> ---
>>> drivers/devfreq/devfreq.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> Found this by hacking device core to call attribute "show" functions
>>> from inside device_add.
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index 00fc23fea5b2..896fb2312f2f 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -1322,11 +1322,11 @@ static ssize_t available_governors_show(struct device *d,
>>>
>>> /*
>>> * The devfreq with immutable governor (e.g., passive) shows
>>> * only own governor.
>>> */
>>> - if (df->governor->immutable) {
>>> + if (df->governor && df->governor->immutable) {
>>> count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
>>> "%s ", df->governor_name);
>>> /*
>>> * The devfreq device shows the registered governor except for
>>> * immutable governors such as passive governor .
>>>
>>
>> As you mentioned, it create sysfs and then initialize the governor instance
>> as following:
>>
>> device_register()
>> device_add()
>> device_add_attrs()
>> creating sysfs entries.
>> governor = try_then_request_governor(...)
>>
>>
>> Thanks for fix-up.
>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>>
>> Additionally, you have to add the following 'fixes' tag
>> and then send it to stable mailing list(stable@vger.kernel.org).
>> - Fixes: bcf23c79c4e46 ("PM / devfreq: Fix available_governor sysfs")
>
> OK, but I'm not sure this meets the criteria for inclusion into linux
> stable:
>
> * It must fix a real bug that bothers people (not a, "This could be a
> problem..." type thing).
> * No "theoretical race condition" issues, unless an explanation of how
> the race can be exploited is also provided.
OK. If you think that it is not necessary to send it to stable mailing list,
don't send it. Thanks.
>
> This patch fixes a theoretical race condition which has been there since
> the start.
>
> --
> Regards,
> Leonard
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 10+ messages in thread