Re: [PATCH net] net: ravb: Fix possible UAF bug in ravb_remove

[Sergei Shtylyov <sergei.shtylyov@gmail.com>]

Hello!

On 9/2/23 5:34 PM, Salvatore Bonaccorso wrote:
[...]
>>>> In ravb_probe, priv->work was bound with ravb_tx_timeout_work.
>>>> If timeout occurs, it will start the work. And if we call
>>>> ravb_remove without finishing the work, ther may be a use
>>>
>>> ther -> there
>>>
>>
>> Sorry about the typo, will correct it in the next version.
>>
>>>> after free bug on ndev.

   BTW, is UAF a common abbreviation? I for one didn't know it...

>>>>
>>>> Fix it by finishing the job before cleanup in ravb_remove.
>>>>
>>>> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
>>>> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
>>>> ---
>>>>  drivers/net/ethernet/renesas/ravb_main.c | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
>>>> index 0f54849a3823..07a08e72f440 100644
>>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>>>> @@ -2892,6 +2892,7 @@ static int ravb_remove(struct platform_device *pdev)
>>>>       struct ravb_private *priv = netdev_priv(ndev);
>>>>       const struct ravb_hw_info *info = priv->info;
>>>>
>>>> +     cancel_work_sync(&priv->work);
>>>
>>> As your previous patch, I still do not see anything stopping
>>> dev_watchdog() from calling dev->netdev_ops->ndo_tx_timeout
>>> after cancel_work_sync(), maybe I missed something obvious
>>> here?
>>>
>> Yes, that's a keyed suggestion. I was hurry to report the issue today
>> so wrote with many mistakes.
>> Thanks agagin for the advice. I will review other patch carefully.
>>
>> Best regards,
>> Zheng
> 
> Looking through some older reports and proposed patches, has this even
> been accepted later?

   No, the latest patch was v4 and it still didn't seem acceptable; I for one
don't agree that Zheng does his things in ravb_remove(), not ravb_close().

> Or did it felt trough the cracks?

   No, there are just too long delays between versions... and the patch still
doesn't seem correct enough... :-/

> Regards,
> Salvatore

MBR, Sergey