Re: [PATCH] usb: dwc3: qcom: fix NULL pointer dereference on dwc3_qcom_read_usb2_speed

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

On Tue, Aug 13, 2024 at 04:48:47PM +0530, Faisal Hassan wrote:
> Null pointer dereference occurs when accessing 'hcd' to detect speed
> from dwc3_qcom_suspend after the xhci-hcd is unbound.
> To avoid this issue, ensure to check for NULL in dwc3_qcom_read_usb2_speed.
> 
> echo xhci-hcd.0.auto > /sys/bus/platform/drivers/xhci-hcd/unbind
>   xhci_plat_remove() -> usb_put_hcd() -> hcd_release() -> kfree(hcd)
> 
>   Unable to handle kernel NULL pointer dereference at virtual address
>   0000000000000060
>   Call trace:
>    dwc3_qcom_suspend.part.0+0x17c/0x2d0 [dwc3_qcom]
>    dwc3_qcom_runtime_suspend+0x2c/0x40 [dwc3_qcom]
>    pm_generic_runtime_suspend+0x30/0x44
>    __rpm_callback+0x4c/0x190
>    rpm_callback+0x6c/0x80
>    rpm_suspend+0x10c/0x620
>    pm_runtime_work+0xc8/0xe0
>    process_one_work+0x1e4/0x4f4
>    worker_thread+0x64/0x43c
>    kthread+0xec/0x100
>    ret_from_fork+0x10/0x20
> 
> Fixes: c5f14abeb52b ("usb: dwc3: qcom: fix peripheral and OTG suspend")
> Cc: stable@vger.kernel.org
> Signed-off-by: Faisal Hassan <quic_faisalh@quicinc.com>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index 88fb6706a18d..0c7846478655 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -319,13 +319,15 @@ static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom)
>  static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom, int port_index)
>  {
>  	struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
> -	struct usb_device *udev;
> +	struct usb_device __maybe_unused *udev;

This change is not relevant to this overall patch, please remove it and
submit it separately if still needed.

thanks,

greg k-h