On Tue, Aug 13, 2024, 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@xxxxxxxxxxxxxxx
> Signed-off-by: Faisal Hassan <quic_faisalh@xxxxxxxxxxx>
> ---
> 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);
What if dwc is not available?
> - struct usb_device *udev;
> + struct usb_device __maybe_unused *udev;
This is odd.... Is there a scenario where you don't want to set
CONFIG_USB if dwc3_qcom is in use?
> struct usb_hcd __maybe_unused *hcd;
>
> /*
> * FIXME: Fix this layering violation.
> */
> hcd = platform_get_drvdata(dwc->xhci);
> + if (!hcd)
> + return USB_SPEED_UNKNOWN;
>
> #ifdef CONFIG_USB
Perhaps this #ifdef shouldn't only be checking this. But that's for
another patch.
> udev = usb_hub_find_child(hcd->self.root_hub, port_index + 1);
> --
> 2.17.1
>
BR,
Thinh
