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[PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()

Hangyu Hua posted 1 patch 2 years, 7 months ago
There is a newer version of this series
net/openvswitch/meter.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
[PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()
Posted by Hangyu Hua 2 years, 7 months ago 
old_meter needs to be free after it is detached regardless of whether
the new meter is successfully attached.

Fixes: c7c4c44c9a95 ("net: openvswitch: expand the meters supported number")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
---

v2: use goto label and free old_meter outside of ovs lock.

 net/openvswitch/meter.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
index 6e38f68f88c2..9b680f0894f1 100644
--- a/net/openvswitch/meter.c
+++ b/net/openvswitch/meter.c
@@ -417,6 +417,7 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
 	int err;
 	u32 meter_id;
 	bool failed;
+	bool locked = true;
 
 	if (!a[OVS_METER_ATTR_ID])
 		return -EINVAL;
@@ -448,11 +449,13 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
 		goto exit_unlock;
 
 	err = attach_meter(meter_tbl, meter);
-	if (err)
-		goto exit_unlock;
 
 	ovs_unlock();
 
+	if (err) {
+		locked = false;
+		goto exit_free_old_meter;
+	}
 	/* Build response with the meter_id and stats from
 	 * the old meter, if any.
 	 */
@@ -472,8 +475,11 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
 	genlmsg_end(reply, ovs_reply_header);
 	return genlmsg_reply(reply, info);
 
+exit_free_old_meter:
+	ovs_meter_free(old_meter);
 exit_unlock:
-	ovs_unlock();
+	if (locked)
+		ovs_unlock();
 	nlmsg_free(reply);
 exit_free_meter:
 	kfree(meter);
-- 
2.34.1
Re: [ovs-dev] [PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()
Posted by Simon Horman 2 years, 7 months ago 
On Thu, Feb 09, 2023 at 05:32:40PM +0800, Hangyu Hua wrote:
> old_meter needs to be free after it is detached regardless of whether
> the new meter is successfully attached.
> 
> Fixes: c7c4c44c9a95 ("net: openvswitch: expand the meters supported number")
> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
> ---
> 
> v2: use goto label and free old_meter outside of ovs lock.
> 
>  net/openvswitch/meter.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
> index 6e38f68f88c2..9b680f0894f1 100644
> --- a/net/openvswitch/meter.c
> +++ b/net/openvswitch/meter.c
> @@ -417,6 +417,7 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>  	int err;
>  	u32 meter_id;
>  	bool failed;
> +	bool locked = true;
>  
>  	if (!a[OVS_METER_ATTR_ID])
>  		return -EINVAL;
> @@ -448,11 +449,13 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>  		goto exit_unlock;
>  
>  	err = attach_meter(meter_tbl, meter);
> -	if (err)
> -		goto exit_unlock;
>  
>  	ovs_unlock();
>  
> +	if (err) {
> +		locked = false;
> +		goto exit_free_old_meter;
> +	}
>  	/* Build response with the meter_id and stats from
>  	 * the old meter, if any.
>  	 */
> @@ -472,8 +475,11 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>  	genlmsg_end(reply, ovs_reply_header);
>  	return genlmsg_reply(reply, info);
>  
> +exit_free_old_meter:
> +	ovs_meter_free(old_meter);
>  exit_unlock:
> -	ovs_unlock();
> +	if (locked)
> +		ovs_unlock();

I see where you are going here, but is the complexity of the
locked variable worth the benefit of freeing old_meter outside
the lock?

>  	nlmsg_free(reply);
>  exit_free_meter:
>  	kfree(meter);
> -- 
> 2.34.1
> 
> _______________________________________________
> dev mailing list
> dev@openvswitch.org
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>
Re: [ovs-dev] [PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()
Posted by Eelco Chaudron 2 years, 7 months ago 

On 9 Feb 2023, at 11:58, Simon Horman wrote:

> On Thu, Feb 09, 2023 at 05:32:40PM +0800, Hangyu Hua wrote:
>> old_meter needs to be free after it is detached regardless of whether
>> the new meter is successfully attached.
>>
>> Fixes: c7c4c44c9a95 ("net: openvswitch: expand the meters supported number")
>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
>> ---
>>
>> v2: use goto label and free old_meter outside of ovs lock.
>>
>>  net/openvswitch/meter.c | 12 +++++++++---
>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
>> index 6e38f68f88c2..9b680f0894f1 100644
>> --- a/net/openvswitch/meter.c
>> +++ b/net/openvswitch/meter.c
>> @@ -417,6 +417,7 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>>  	int err;
>>  	u32 meter_id;
>>  	bool failed;
>> +	bool locked = true;
>>
>>  	if (!a[OVS_METER_ATTR_ID])
>>  		return -EINVAL;
>> @@ -448,11 +449,13 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>>  		goto exit_unlock;
>>
>>  	err = attach_meter(meter_tbl, meter);
>> -	if (err)
>> -		goto exit_unlock;
>>
>>  	ovs_unlock();
>>
>> +	if (err) {
>> +		locked = false;
>> +		goto exit_free_old_meter;
>> +	}
>>  	/* Build response with the meter_id and stats from
>>  	 * the old meter, if any.
>>  	 */
>> @@ -472,8 +475,11 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>>  	genlmsg_end(reply, ovs_reply_header);
>>  	return genlmsg_reply(reply, info);
>>
>> +exit_free_old_meter:
>> +	ovs_meter_free(old_meter);
>>  exit_unlock:
>> -	ovs_unlock();
>> +	if (locked)
>> +		ovs_unlock();
>
> I see where you are going here, but is the complexity of the
> locked variable worth the benefit of freeing old_meter outside
> the lock?

Looking at the error path, I would agree with Simon, and just add an “exit_free_old_meter” label as suggested in v1 and keep the lock in place to make the error path more straightforward.

//Eelco

>>  	nlmsg_free(reply);
>>  exit_free_meter:
>>  	kfree(meter);
>> -- 
>> 2.34.1
>>
>> _______________________________________________
>> dev mailing list
>> dev@openvswitch.org
>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>
Re: [ovs-dev] [PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()
Posted by Hangyu Hua 2 years, 7 months ago 
On 9/2/2023 21:42, Eelco Chaudron wrote:
> 
> 
> On 9 Feb 2023, at 11:58, Simon Horman wrote:
> 
>> On Thu, Feb 09, 2023 at 05:32:40PM +0800, Hangyu Hua wrote:
>>> old_meter needs to be free after it is detached regardless of whether
>>> the new meter is successfully attached.
>>>
>>> Fixes: c7c4c44c9a95 ("net: openvswitch: expand the meters supported number")
>>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
>>> ---
>>>
>>> v2: use goto label and free old_meter outside of ovs lock.
>>>
>>>   net/openvswitch/meter.c | 12 +++++++++---
>>>   1 file changed, 9 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
>>> index 6e38f68f88c2..9b680f0894f1 100644
>>> --- a/net/openvswitch/meter.c
>>> +++ b/net/openvswitch/meter.c
>>> @@ -417,6 +417,7 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>>>   	int err;
>>>   	u32 meter_id;
>>>   	bool failed;
>>> +	bool locked = true;
>>>
>>>   	if (!a[OVS_METER_ATTR_ID])
>>>   		return -EINVAL;
>>> @@ -448,11 +449,13 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>>>   		goto exit_unlock;
>>>
>>>   	err = attach_meter(meter_tbl, meter);
>>> -	if (err)
>>> -		goto exit_unlock;
>>>
>>>   	ovs_unlock();
>>>
>>> +	if (err) {
>>> +		locked = false;
>>> +		goto exit_free_old_meter;
>>> +	}
>>>   	/* Build response with the meter_id and stats from
>>>   	 * the old meter, if any.
>>>   	 */
>>> @@ -472,8 +475,11 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
>>>   	genlmsg_end(reply, ovs_reply_header);
>>>   	return genlmsg_reply(reply, info);
>>>
>>> +exit_free_old_meter:
>>> +	ovs_meter_free(old_meter);
>>>   exit_unlock:
>>> -	ovs_unlock();
>>> +	if (locked)
>>> +		ovs_unlock();
>>
>> I see where you are going here, but is the complexity of the
>> locked variable worth the benefit of freeing old_meter outside
>> the lock?
> 
> Looking at the error path, I would agree with Simon, and just add an “exit_free_old_meter” label as suggested in v1 and keep the lock in place to make the error path more straightforward.
> 
> //Eelco

I see. I will send a v3 later.

Thanks,
Hangyu

> 
>>>   	nlmsg_free(reply);
>>>   exit_free_meter:
>>>   	kfree(meter);
>>> -- 
>>> 2.34.1
>>>
>>> _______________________________________________
>>> dev mailing list
>>> dev@openvswitch.org
>>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>>
>

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