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SubjectRe: [PATCH] drivers: net: remove a dangling pointer in peak_usb_create_dev
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Hi Dongliang,

On 1/21/22 08:58, Dongliang Mu wrote:
[...]>> BTW, as you mentioned, dev->next_siblings is used in struct
>> peak_usb_adapter::dev_free() (i.e., pcan_usb_fd_free or
>> pcan_usb_pro_free), how about the following path?
>>
>> peak_usb_probe
>> -> peak_usb_create_dev (goto adap_dev_free;)
>> -> dev->adapter->dev_free()
>> -> pcan_usb_fd_free or pcan_usb_pro_free (This function uses
>> next_siblings as condition elements)
>>
>> static void pcan_usb_fd_free(struct peak_usb_device *dev)
>> {
>> /* last device: can free shared objects now */
>> if (!dev->prev_siblings && !dev->next_siblings) {
>> struct pcan_usb_fd_device *pdev =
>> container_of(dev, struct pcan_usb_fd_device, dev);
>>
>> /* free commands buffer */
>> kfree(pdev->cmd_buffer_addr);
>>
>> /* free usb interface object */
>> kfree(pdev->usb_if);
>> }
>> }
>>
>> If next_siblings is not NULL, will it lead to the missing free of
>> cmd_buffer_addr and usb_if?
>
> The answer is No. Forget my silly thought.
>

Yeah, it seems like (at least based on code), that this dangling pointer
is not dangerous, since nothing accesses it. And next_siblings
_guaranteed_ to be NULL, since dev->next_siblings is set NULL in
disconnect()




With regards,
Pavel Skripkin

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