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);
return NULL;
On Saturday 08 February 2014 16:45:06 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(+)
Applied in revision cb4d66e.
Thanks, Marek
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?
Cheers,
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...
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,
On Tuesday 11 February 2014 18:34:10 Antonio Quartulli wrote:
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.
It may be safe now but will surely be forgotten later. A guaranteed source for trouble. That is why we have cleanup routines for everything.
Cheers, Marek
On 11/02/14 18:40, Marek Lindner wrote:
On Tuesday 11 February 2014 18:34:10 Antonio Quartulli wrote:
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.
It may be safe now but will surely be forgotten later. A guaranteed source for trouble. That is why we have cleanup routines for everything.
True, in particular because we (as bat_iv_ogm.c) do not know what batadv_orig_node_new() has allocated - a kfree() would be fine if the object was allocated with a plain kmalloc(), but this is not the case.
By the way we have a bug here: if we jump to
256 free_bcast_own: 257 kfree(orig_node->bat_iv.bcast_own);
bcast_own gets free'd but not assigned to NULL. Later batadv_orig_node_free_rcu() (scheduled by batadv_orig_node_free_ref()) will call batadv_iv_ogm_orig_free() that will try to kfree() bcast_own again (line 98 in bat_iv_ogm.c), thus leading to a double free. no?
Cheers,
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?
What about already allocated substructures like bat_iv.bcast_own, bat_iv.bacst_own_sum etc? Of course we could find out which is already allocated and free that too, but that orig node free function does already that.
Cheers, Simon
b.a.t.m.a.n@lists.open-mesh.org
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Antonio Quartulli -
Marek Lindner -
Martin Hundebøll -
Simon Wunderlich