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SubjectRe: [PATCH -next 2/3] PCI: fix possible memory leak in error case in pci_register_host_bridge()
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On 2022/8/27 6:38, Bjorn Helgaas wrote:
> [+cc Arnd, Rob]
>
> On Thu, Aug 25, 2022 at 08:27:52PM +0800, Yang Yingliang wrote:
>> If device_register() fails in pci_register_host_bridge(), the refcount
>> of bus device is leaked, so device name that set by dev_set_name() can
>> not be freed. Fix this by calling put_device() when device_register()
>> fails, so the device name will be freed in kobject_cleanup().
>>
>> Fixes: 37d6a0a6f470 ("PCI: Add pci_register_host_bridge() interface")
>> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
>> ---
>> drivers/pci/probe.c | 17 +++++++++++------
>> 1 file changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index e500eb9d6468..292d9da146ce 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -948,8 +948,17 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
>> name = dev_name(&bus->dev);
>>
>> err = device_register(&bus->dev);
>> - if (err)
>> - goto unregister;
>> + if (err) {
>> + /*
>> + * release_pcibus_dev() will decrease the refcount of bridge
>> + * device and free the memory of bus.
>> + * The memory of bus device name will be freed when the refcount
>> + * get to zero.
>> + */
>> + put_device(&bus->dev);
>> + device_unregister(&bridge->dev);
>> + return err;
>> + }
> Calling put_device(X) after device_register(X) returns failure doesn't
> need explanation because that's the standard pattern. I think that
> was just missing before.
>
> In this error case, we previously did called put_device() for the
> *bridge* instead of the bus. That was likely a typo and seems like
> the important thing here.
put_device() for the bridge will be called in the callback of put for
the bus.
So it doesn't call put bridge device here.

Thanks,
Yang
>> pcibios_add_bus(bus);
>>
>> @@ -1025,10 +1034,6 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
>>
>> return 0;
>>
>> -unregister:
>> - put_device(&bridge->dev);
>> - device_unregister(&bridge->dev);
>> -
>> free:
>> kfree(bus);
>> return err;
>> --
>> 2.25.1
>>
> .

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