From: Pavel Skripkin <paskripkin@gmail•com>
To: Dongliang Mu <mudongliangabcd@gmail•com>
Cc: "Dongliang Mu" <dzm91@hust•edu.cn>,
"Wolfgang Grandegger" <wg@grandegger•com>,
"Marc Kleine-Budde" <mkl@pengutronix•de>,
"David S. Miller" <davem@davemloft•net>,
"Jakub Kicinski" <kuba@kernel•org>,
"Stephane Grosjean" <s.grosjean@peak-system•com>,
"Stefan Mätje" <stefan.maetje@esd•eu>,
"Vincent Mailhol" <mailhol.vincent@wanadoo•fr>,
linux-can@vger•kernel.org,
"open list:NETWORKING [GENERAL]" <netdev@vger•kernel.org>,
linux-kernel <linux-kernel@vger•kernel.org>
Subject: Re: [PATCH] drivers: net: remove a dangling pointer in peak_usb_create_dev
Date: Fri, 21 Jan 2022 22:36:45 +0300 [thread overview]
Message-ID: <8d4b0822-4e94-d124-e191-bec3effaf97c@gmail.com> (raw)
In-Reply-To: <CAD-N9QUZ95zqboe=58gybue6ssSO-M-raijd3XnGXkXnp3wiqQ@mail.gmail.com>
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
next prev parent reply other threads:[~2022-01-21 19:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-20 13:05 [PATCH] drivers: net: remove a dangling pointer in peak_usb_create_dev Dongliang Mu
2022-01-20 14:27 ` Pavel Skripkin
2022-01-21 0:09 ` Dongliang Mu
2022-01-21 3:36 ` Dongliang Mu
2022-01-21 5:58 ` Dongliang Mu
2022-01-21 19:36 ` Pavel Skripkin [this message]
2022-01-22 6:45 ` Dongliang Mu
2022-01-23 13:48 ` Pavel Skripkin
2022-01-24 6:04 ` Dongliang Mu
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