[PATCH 1/3] of: fix of_node leak caused in of_find_node_opts_by_path

[PATCH 1/3] of: fix of_node leak caused in of_find_node_opts_by_path

[Qi Hou]

During stepping down the tree, parent node is gotten first and its refcount is
increased with of_node_get() in __of_get_next_child(). Since it just being used
as tmp node, its refcount must be decreased with of_node_put() after traversing
its child nodes.

Or, its refcount will never be descreased to ZERO, then it will never be freed,
as well as other related memory blocks.

To fix this, decrease refcount of parent with of_node_put() after
__of_find_node_by_path().

Signed-off-by: Qi Hou <qi.hou@windriver.com>
Acked-by: Peter Rosin <peda@axentia.se>
---
 drivers/of/base.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index d4bea3c..ce8206f 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -842,8 +842,11 @@ struct device_node *of_find_node_opts_by_path(const char *path, const char **opt
 	if (!np)
 		np = of_node_get(of_root);
 	while (np && *path == '/') {
+		struct device_node *tmp = np;
+
 		path++; /* Increment past '/' delimiter */
 		np = __of_find_node_by_path(np, path);
+		of_node_put(tmp);
 		path = strchrnul(path, '/');
 		if (separator && separator < path)
 			break;
-- 
1.9.1

Re: [PATCH 1/3] of: fix of_node leak caused in of_find_node_opts_by_path

[Rob Herring]

On Sun, Feb 5, 2017 at 10:55 PM, Qi Hou <qi.hou@windriver.com> wrote:
> During stepping down the tree, parent node is gotten first and its refcount is
> increased with of_node_get() in __of_get_next_child(). Since it just being used
> as tmp node, its refcount must be decreased with of_node_put() after traversing
> its child nodes.
>
> Or, its refcount will never be descreased to ZERO, then it will never be freed,
> as well as other related memory blocks.
>
> To fix this, decrease refcount of parent with of_node_put() after
> __of_find_node_by_path().
>
> Signed-off-by: Qi Hou <qi.hou@windriver.com>
> Acked-by: Peter Rosin <peda@axentia.se>
> ---
>  drivers/of/base.c | 3 +++
>  1 file changed, 3 insertions(+)

It doesn't look like there is any inter-dependency with this patch and
the other 2, so I'll apply this one.

Rob

Re: [PATCH 1/3] of: fix of_node leak caused in of_find_node_opts_by_path

[qhou]

On 2017年02月09日 23:11, Rob Herring wrote:
> On Sun, Feb 5, 2017 at 10:55 PM, Qi Hou <qi.hou@windriver.com> wrote:
>> During stepping down the tree, parent node is gotten first and its refcount is
>> increased with of_node_get() in __of_get_next_child(). Since it just being used
>> as tmp node, its refcount must be decreased with of_node_put() after traversing
>> its child nodes.
>>
>> Or, its refcount will never be descreased to ZERO, then it will never be freed,
>> as well as other related memory blocks.
>>
>> To fix this, decrease refcount of parent with of_node_put() after
>> __of_find_node_by_path().
>>
>> Signed-off-by: Qi Hou <qi.hou@windriver.com>
>> Acked-by: Peter Rosin <peda@axentia.se>
>> ---
>>   drivers/of/base.c | 3 +++
>>   1 file changed, 3 insertions(+)
> It doesn't look like there is any inter-dependency with this patch and
> the other 2, so I'll apply this one.
No, there is no inter-dependency in these three patches.

Just since they are all related with of_node_put and reported by 
kmemleak and debugged
by the similar means, I sent them together.

-- Best regards,
Qi Hou
>
> Rob