Re: [PATCH V2] drivers: nfc: nfcmrvl: fix double free bug in nfcmrvl_nci_unregister_dev()

[Krzysztof Kozlowski]

On 10/04/2022 15:52, Duoming Zhou wrote:
> There is a potential double bug in nfcmrvl usb driver between
> unregister and resume operation.
> 
> The race that cause that double free bug can be shown as below:
> 
>    (FREE)                   |      (USE)
>                             | nfcmrvl_resume
>                             |  nfcmrvl_submit_bulk_urb
>                             |   nfcmrvl_bulk_complete
>                             |    nfcmrvl_nci_recv_frame
>                             |     nfcmrvl_fw_dnld_recv_frame
>                             |      queue_work
>                             |       fw_dnld_rx_work
>                             |        fw_dnld_over
>                             |         release_firmware
>                             |          kfree(fw); //(1)
> nfcmrvl_disconnect          |
>  nfcmrvl_nci_unregister_dev |
>   nfcmrvl_fw_dnld_abort     |
>    fw_dnld_over             |         ...
>     if (priv->fw_dnld.fw)   |
>     release_firmware        |
>      kfree(fw); //(2)       |
>      ...                    |         priv->fw_dnld.fw = NULL;
> 


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>


Best regards,
Krzysztof