Re: [PATCH v3] device property: fix of node refcount leak in fwnode_graph_get_next_endpoint()

Yang Yingliang
2022-11-25T09:52:01Z

On 2022/11/25 17:32, Daniel Scally wrote:
> Hello
>
> On 23/11/2022 13:31, Andy Shevchenko wrote:
>> On Wed, Nov 23, 2022 at 10:25:42AM +0800, Yang Yingliang wrote:
>>> The 'parent' returned by fwnode_graph_get_port_parent()
>>> with refcount incremented when 'prev' is not NULL, it
>>> needs be put when finish using it.
>>>
>>> Because the parent is const, introduce a new variable to
>>> store the returned fwnode, then put it before returning
>>> from fwnode_graph_get_next_endpoint().
>> To me this looks good enough. Not sure if Dan has a chance (time) to look at
>> this, though. And maybe even test...
>>
>> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>
> Apologies; didn't notice this earlier. I will look at and test this today

Thanks,

I tested it, without this patch, I got this message:
OF: ERROR: memory leak, expected refcount 1 instead of 4,
of_node_get()/of_node_put() unbalanced - destroy cset entry: attach
overlay node /i2c/pmic@34/tcpc/connector
after this patch,  the message is gone.
>
>>> Fixes: b5b41ab6b0c1 ("device property: Check fwnode->secondary in fwnode_graph_get_next_endpoint()")
>>> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
>>> ---
>>> v2 -> v3:
>>> Add a out label.
>>>
>>> v1 -> v2:
>>> Introduce a new variable to store the returned fwnode.
>>> ---
>>> drivers/base/property.c | 18 ++++++++++++------
>>> 1 file changed, 12 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/base/property.c b/drivers/base/property.c
>>> index 2a5a37fcd998..7f338cb4fb7b 100644
>>> --- a/drivers/base/property.c
>>> +++ b/drivers/base/property.c
>>> @@ -989,26 +989,32 @@ struct fwnode_handle *
>>> fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
>>> struct fwnode_handle *prev)
>>> {
>>> + struct fwnode_handle *ep, *port_parent = NULL;
>>> const struct fwnode_handle *parent;
>>> - struct fwnode_handle *ep;
>>>
>>> /*
>>> * If this function is in a loop and the previous iteration returned
>>> * an endpoint from fwnode->secondary, then we need to use the secondary
>>> * as parent rather than @fwnode.
>>> */
>>> - if (prev)
>>> - parent = fwnode_graph_get_port_parent(prev);
>>> - else
>>> + if (prev) {
>>> + port_parent = fwnode_graph_get_port_parent(prev);
>>> + parent = port_parent;
>>> + } else {
>>> parent = fwnode;
>>> + }
>>> if (IS_ERR_OR_NULL(parent))
>>> return NULL;
>>>
>>> ep = fwnode_call_ptr_op(parent, graph_get_next_endpoint, prev);
>>> if (ep)
>>> - return ep;
>>> + goto out_put_port_parent;
>>> +
>>> + ep = fwnode_graph_get_next_endpoint(parent->secondary, NULL);
>>>
>>> - return fwnode_graph_get_next_endpoint(parent->secondary, NULL);
>>> +out_put_port_parent:
>>> + fwnode_handle_put(port_parent);
>>> + return ep;
>>> }
>>> EXPORT_SYMBOL_GPL(fwnode_graph_get_next_endpoint);
>>>
>>> --
>>> 2.25.1
>>>
> .