[U-Boot] [PATCH] usb: xhci: Fix a potential NULL pointer dereference

[Marek Vasut]

On Friday, August 14, 2015 at 02:13:06 PM, Sergey Temerkhanov wrote:
> This patch fixes a potential NULL pointer dereference arising on
> non-present/non-initialized xHCI controllers

Hi,

can you please explain how can such a condition even happen ?
I believe the hcor must always be inited at that point. What
is the condition which triggers this ?

> Signed-off-by: Sergey Temerkhanov <s.temerkhanov at gmail.com>
> Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla at cavium.com>
> ---
> 
>  drivers/usb/host/xhci.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 0b09643..a6c6659 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -199,7 +199,7 @@ int xhci_reset(struct xhci_hcor *hcor)
>  	int ret;
> 
>  	/* Halting the Host first */
> -	debug("// Halt the HC\n");
> +	debug("// Halt the HC: %p\n", hcor);
>  	state = xhci_readl(&hcor->or_usbsts) & STS_HALT;
>  	if (!state) {
>  		cmd = xhci_readl(&hcor->or_usbcmd);
> @@ -1093,9 +1093,11 @@ int usb_lowlevel_stop(int index)
>  {
>  	struct xhci_ctrl *ctrl = (xhcic + index);
> 
> -	xhci_lowlevel_stop(ctrl);
> -	xhci_hcd_stop(index);
> -	xhci_cleanup(ctrl);
> +	if (ctrl->hcor) {
> +		xhci_lowlevel_stop(ctrl);
> +		xhci_hcd_stop(index);
> +		xhci_cleanup(ctrl);
> +	}
> 
>  	return 0;
>  }

Best regards,
Marek Vasut