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
