Re: [PATCH] usb: cdnsp: Fix potential dereference of NULL pointer

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, May 18, 2022 at 09:35:43AM -0700, Yongzhi Liu wrote:
> The return value of cdnsp_get_transfer_ring()
> needs to be checked to avoid use of NULL pointer
> in case of an acquisition failure.

Please use the full 72 columns

> 
> Fixes: 3d8290455 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
> 
> Signed-off-by: Yongzhi Liu <lyz_cs@pku.edu.cn>

Please do not put a blank line between "Fixes:" and your signed off by
line.

> ---
>  drivers/usb/cdns3/cdnsp-ring.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
> index 1b14384..9f206b9 100644
> --- a/drivers/usb/cdns3/cdnsp-ring.c
> +++ b/drivers/usb/cdns3/cdnsp-ring.c
> @@ -655,6 +655,8 @@ static int cdnsp_cmd_set_deq(struct cdnsp_device *pdev,
>  	 * to reflect the new position.
>  	 */
>  	ep_ring = cdnsp_get_transfer_ring(pdev, pep, deq_state->stream_id);
> +	if (!ep_ring)
> +		return -EINVAL;

How did you test this?

Don't you need to properly clean up and handle the hardware issues if
you exit early here?

Without good testing, I am loath to take this.

thanks,

greg k-h