Re: [B.A.T.M.A.N.] [PATCH-maint] batman-adv: fix potential orig_node reference leak

[Antonio Quartulli <antonio@meshcoding.com>]

[-- Attachment #1: Type: text/plain, Size: 1880 bytes --]

On 11/02/14 18:29, Martin Hundebøll wrote:
> On 2014-02-11 18:26, Antonio Quartulli wrote:
>> On 08/02/14 16:45, Simon Wunderlich wrote:
>>> Since batadv_orig_node_new() sets the refcount to two, assuming that
>>> the calling function will use a reference for putting the orig_node into
>>> a hash or similar, both references must be freed if initialization of
>>> the orig_node fails. Otherwise that object may be leaked in that error
>>> case.
>>>
>>> Reported-by: Antonio Quartulli <antonio@meshcoding.com>
>>> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
>>> ---
>>>  bat_iv_ogm.c |    2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/bat_iv_ogm.c b/bat_iv_ogm.c
>>> index 6f4fcdc..6000337 100644
>>> --- a/bat_iv_ogm.c
>>> +++ b/bat_iv_ogm.c
>>> @@ -256,6 +256,8 @@ batadv_iv_ogm_orig_get(struct batadv_priv *bat_priv, const uint8_t *addr)
>>>  free_bcast_own:
>>>  	kfree(orig_node->bat_iv.bcast_own);
>>>  free_orig_node:
>>> +	/* free twice, as batadv_orig_node_new set refcount to 2 */
>>> +	batadv_orig_node_free_ref(orig_node);
>>>  	batadv_orig_node_free_ref(orig_node);
>>
>> Coudln't we just invoke kfree(orig_node) here ? I think that if we hit
>> this point it is because the node has not added to the hash and
>> therefore it i snot used in any other context. This way we avoid the
>> double free_ref() and we don't trgger the whole RCU mechanism.
>>
>> Or am I missing something?
> 
> batadv_<type>_free_ref() might have side effect that are not handled by
> kfree alone...

true, but since the orig_node has not been returned yet there is no
other component in batman-adv which is using it.

Otherwise, we may want to define and invoke a free_now() version of this
function (like we have done for other objects). But I think kfree() is
safe here.


Cheers,



-- 
Antonio Quartulli


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]