Re: [PATCH] ntb: ntb_hw_switchtec: Fix use after free vulnerability in switchtec_ntb_remove due to race condition

[Kaixin Wang]

At 2024-09-10 02:17:57, "Logan Gunthorpe" <logang@xxxxxxxxxxxx> wrote:
>
>
>On 2024-09-09 11:20, Kaixin Wang wrote:
>> In the switchtec_ntb_add function, it can call switchtec_ntb_init_sndev
>> function, then &sndev->check_link_status_work is bound with
>> check_link_status_work. switchtec_ntb_link_notification may be called
>> to start the work.
>> 
>> If we remove the module which will call switchtec_ntb_remove to make
>> cleanup, it will free sndev through kfree(sndev), while the work
>> mentioned above will be used. The sequence of operations that may lead
>> to a UAF bug is as follows:
>> 
>> CPU0                                 CPU1
>> 
>>                         | check_link_status_work
>> switchtec_ntb_remove    |
>> kfree(sndev);           |
>>                         | if (sndev->link_force_down)
>>                         | // use sndev
>> 
>> Fix it by ensuring that the work is canceled before proceeding with
>> the cleanup in switchtec_ntb_remove.
>
>Thank you, this looks good to me.
>
>Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
>

Thanks for the review!

Best regards,
Kaixin Wang