2023-02-09 09:33:16

by Hangyu Hua

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

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 <[email protected]>
---

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

2023-02-09 10:59:28

by Simon Horman

Subject: Re: [ovs-dev] [PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()

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 <[email protected]>
> ---
>
> 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
> [email protected]
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>

2023-02-09 13:44:20

by Eelco Chaudron

Subject: Re: [ovs-dev] [PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()

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 <[email protected]>
>> ---
>>
>> 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
>> [email protected]
>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>

2023-02-10 01:52:38

by Hangyu Hua

Subject: Re: [ovs-dev] [PATCH v2] net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()

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 <[email protected]>
>>> ---
>>>
>>> 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
>>> [email protected]
>>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>>
>