* [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store
@ 2017-12-06 20:20 ` Gustavo A. R. Silva
2017-12-07 1:24 ` Chanwoo Choi
2017-12-07 2:41 ` MyungJoo Ham
0 siblings, 2 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2017-12-06 20:20 UTC (permalink / raw)
To: MyungJoo Ham, Kyungmin Park, Chanwoo Choi
Cc: linux-pm, linux-kernel, Gustavo A. R. Silva
df->governor is being dereferenced before it is null checked,
hence there is a potential null pointer dereference.
Notice that df->governor is being null checked at line 1004:
if (df->governor) {, which implies it might be null.
Fix this by null checking df->governor before dereferencing it.
Addresses-Coverity-ID: 1401988 ("Dereference before null check")
Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
drivers/devfreq/devfreq.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 78fb496..14fe76b 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -996,7 +996,8 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
if (df->governor == governor) {
ret = 0;
goto out;
- } else if (df->governor->immutable || governor->immutable) {
+ } else if ((df->governor && df->governor->immutable) ||
+ governor->immutable) {
ret = -EINVAL;
goto out;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store
2017-12-06 20:20 ` [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store Gustavo A. R. Silva
@ 2017-12-07 1:24 ` Chanwoo Choi
2017-12-07 23:56 ` Gustavo A. R. Silva
2017-12-07 2:41 ` MyungJoo Ham
1 sibling, 1 reply; 5+ messages in thread
From: Chanwoo Choi @ 2017-12-07 1:24 UTC (permalink / raw)
To: Gustavo A. R. Silva, MyungJoo Ham, Kyungmin Park; +Cc: linux-pm, linux-kernel
On 2017년 12월 07일 05:20, Gustavo A. R. Silva wrote:
> df->governor is being dereferenced before it is null checked,
> hence there is a potential null pointer dereference.
>
> Notice that df->governor is being null checked at line 1004:
> if (df->governor) {, which implies it might be null.
>
> Fix this by null checking df->governor before dereferencing it.
>
> Addresses-Coverity-ID: 1401988 ("Dereference before null check")
> Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs")
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> ---
> drivers/devfreq/devfreq.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 78fb496..14fe76b 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -996,7 +996,8 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
> if (df->governor == governor) {
> ret = 0;
> goto out;
> - } else if (df->governor->immutable || governor->immutable) {
> + } else if ((df->governor && df->governor->immutable) ||
> + governor->immutable) {
> ret = -EINVAL;
> goto out;
> }
>
Actually, df->governor would be never NULL because devfreq_add_device()
initializes the ->governor always. But, governor_store() doesn't know it.
So, looks good to me.
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
^ permalink raw reply [flat|nested] 5+ messages in thread
* RE: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store
2017-12-06 20:20 ` [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store Gustavo A. R. Silva
2017-12-07 1:24 ` Chanwoo Choi
@ 2017-12-07 2:41 ` MyungJoo Ham
2017-12-07 23:57 ` Gustavo A. R. Silva
1 sibling, 1 reply; 5+ messages in thread
From: MyungJoo Ham @ 2017-12-07 2:41 UTC (permalink / raw)
To: Kyungmin Park, Chanwoo Choi
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
Gustavo A. R. Silva
> df->governor is being dereferenced before it is null checked,
> hence there is a potential null pointer dereference.
>
> Notice that df->governor is being null checked at line 1004:
> if (df->governor) {, which implies it might be null.
>
> Fix this by null checking df->governor before dereferencing it.
>
> Addresses-Coverity-ID: 1401988 ("Dereference before null check")
> Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs")
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Cheers,
MyungJoo
> ---
> drivers/devfreq/devfreq.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 78fb496..14fe76b 100644
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store
2017-12-07 1:24 ` Chanwoo Choi
@ 2017-12-07 23:56 ` Gustavo A. R. Silva
0 siblings, 0 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2017-12-07 23:56 UTC (permalink / raw)
To: Chanwoo Choi; +Cc: MyungJoo Ham, Kyungmin Park, linux-pm, linux-kernel
Hi Chanwoo,
Quoting Chanwoo Choi <cw00.choi@samsung.com>:
> On 2017년 12월 07일 05:20, Gustavo A. R. Silva wrote:
>> df->governor is being dereferenced before it is null checked,
>> hence there is a potential null pointer dereference.
>>
>> Notice that df->governor is being null checked at line 1004:
>> if (df->governor) {, which implies it might be null.
>>
>> Fix this by null checking df->governor before dereferencing it.
>>
>> Addresses-Coverity-ID: 1401988 ("Dereference before null check")
>> Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs")
>> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>> ---
>> drivers/devfreq/devfreq.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 78fb496..14fe76b 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -996,7 +996,8 @@ static ssize_t governor_store(struct device
>> *dev, struct device_attribute *attr,
>> if (df->governor == governor) {
>> ret = 0;
>> goto out;
>> - } else if (df->governor->immutable || governor->immutable) {
>> + } else if ((df->governor && df->governor->immutable) ||
>> + governor->immutable) {
>> ret = -EINVAL;
>> goto out;
>> }
>>
>
> Actually, df->governor would be never NULL because devfreq_add_device()
> initializes the ->governor always. But, governor_store() doesn't know it.
>
I got it.
> So, looks good to me.
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>
Thank you
--
Gustavo A. R. Silva
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store
2017-12-07 2:41 ` MyungJoo Ham
@ 2017-12-07 23:57 ` Gustavo A. R. Silva
0 siblings, 0 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2017-12-07 23:57 UTC (permalink / raw)
To: MyungJoo Ham; +Cc: Kyungmin Park, Chanwoo Choi, linux-pm, linux-kernel
Quoting MyungJoo Ham <myungjoo.ham@samsung.com>:
>> df->governor is being dereferenced before it is null checked,
>> hence there is a potential null pointer dereference.
>>
>> Notice that df->governor is being null checked at line 1004:
>> if (df->governor) {, which implies it might be null.
>>
>> Fix this by null checking df->governor before dereferencing it.
>>
>> Addresses-Coverity-ID: 1401988 ("Dereference before null check")
>> Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs")
>> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>
> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
>
Thank you, MyungJoo
--
Gustavo A. R. Silva
^ permalink raw reply [flat|nested] 5+ messages in thread
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2017-12-06 20:20 ` [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store Gustavo A. R. Silva
2017-12-07 1:24 ` Chanwoo Choi
2017-12-07 23:56 ` Gustavo A. R. Silva
2017-12-07 2:41 ` MyungJoo Ham
2017-12-07 23:57 ` Gustavo A. R. Silva
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