linux-kernel - Re: [PATCH] usb: cdns3: host: Add null check for host

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Message-ID: <2026011935-ransack-unworldly-7cf5@gregkh>
Date: Mon, 19 Jan 2026 10:33:31 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Abhash Kumar Jha <a-kumar2@...com>
Cc: pawell@...ence.com, peter.chen@...nel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, rogerq@...nel.org, u-kumar1@...com,
	p-mantena@...com, theo.lebrun@...tlin.com
Subject: Re: [PATCH] usb: cdns3: host: Add null check for host_device before
 accessing its members

On Mon, Jan 19, 2026 at 01:52:42PM +0530, Abhash Kumar Jha wrote:
> In cases when the xhci device is not populated, we see a nullptr
> exception when resuming.

How can that happen?  What changed to cause this?

> Add a nullptr check for the host_dev before accessing its private data.
> 
> Fixes: 3a85c1011540 ("usb: host: cdns3: forward lost power information to xhci")

No cc: stable?

> Signed-off-by: Abhash Kumar Jha <a-kumar2@...com>
> ---
>  drivers/usb/cdns3/host.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/cdns3/host.c b/drivers/usb/cdns3/host.c
> index f0df114c2b53b..8cc7fc1de6193 100644
> --- a/drivers/usb/cdns3/host.c
> +++ b/drivers/usb/cdns3/host.c
> @@ -141,9 +141,12 @@ static void cdns_host_exit(struct cdns *cdns)
>  static int cdns_host_resume(struct cdns *cdns, bool power_lost)
>  {
>  	struct usb_hcd *hcd = platform_get_drvdata(cdns->host_dev);
> -	struct xhci_plat_priv *priv = hcd_to_xhci_priv(hcd);
> +	struct xhci_plat_priv *priv;
>  
> -	priv->power_lost = power_lost;
> +	if (hcd) {
> +		priv = hcd_to_xhci_priv(hcd);
> +		priv->power_lost = power_lost;
> +	}

Shouldn't you be returning an error if something went wrong?

And what protects hcd from changing right after you tested it?

thanks,

greg k-h