Re: [PATCH] usb: dwc2: remove useless check of !chan

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, May 19, 2026 at 02:00:01PM +0800, Jisheng Zhang wrote:
> It looks a bit strange we check !chan after dereference of this pointer
> with "if (chan->ep_type != USB_ENDPOINT_XFER_CONTROL)".
> 
> In fact, when entering the dwc2_hcd_save_data_toggle(), the chan won't
> be NULL, because its caller or indirect caller has ensured this,
> specifically, it's checked with below line in dwc2_hc_n_intr()
> 
> if (!chan) {
>     dev_err(hsotg->dev, "## hc_ptr_array for channel is NULL ##\n");
>     return;
> }
> 
> This addresses the following issue reported by klocwork tool:
>   - Suspicious dereference of pointer 'chan' before NULL check at
>     line 518
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  drivers/usb/dwc2/hcd_intr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c
> index 5c7538d498dd..397c63393c7f 100644
> --- a/drivers/usb/dwc2/hcd_intr.c
> +++ b/drivers/usb/dwc2/hcd_intr.c
> @@ -515,7 +515,7 @@ void dwc2_hcd_save_data_toggle(struct dwc2_hsotg *hsotg,
>  	u32 pid = (hctsiz & TSIZ_SC_MC_PID_MASK) >> TSIZ_SC_MC_PID_SHIFT;
>  
>  	if (chan->ep_type != USB_ENDPOINT_XFER_CONTROL) {
> -		if (WARN(!chan || !chan->qh,
> +		if (WARN(!chan->qh,
>  			 "chan->qh must be specified for non-control eps\n"))
>  			return;

Can this ever actually happen?  If so, the machine just rebooted as
almost all devices with this hardware in it run with panic-on-warn
enabled.  If not, can you fix this up to properly handle the error and
return correctly and not crash?

thanks,

greg k-h